Fixes the following GCC 5 warnings:
```
core/os/file_access.cpp:49:19: warning: the address of 'FileAccess::create_func' will always evaluate as 'true' [-Waddress]
servers/audio_server.cpp:192:70: warning: comparison with string literal results in unspecified behaviour [-Waddress]
drivers/gles2/rasterizer_storage_gles2.cpp:4095:90: warning: NULL used in arithmetic [-Wpointer-arith]
modules/gdnative/register_types.cpp:237:3: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
platform/android/export/export.cpp:207:1: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
modules/gdscript/gdscript.h:150:67: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:119:56: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:123:56: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:127:50: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:131:52: warning: returning reference to temporary [-Wreturn-local-addr]
editor/plugins/skeleton_editor_plugin.cpp:34:36: warning: extra tokens at end of #include directive
modules/bullet/bullet_types_converter.cpp:31:9: warning: #pragma once in main file
editor/import/editor_scene_importer_gltf.cpp:1996:51: warning: name lookup of 'i' changed
modules/visual_script/visual_script_property_selector.cpp:402:45: warning: name lookup of 'E' changed
scene/gui/tree.cpp:1268:25: warning: name lookup of 'i' changed
scene/resources/visual_shader.cpp:808:32: warning: name lookup of 'i' changed
```
Fixes the following GCC 5 warnings:
```
drivers/gles2/rasterizer_canvas_gles2.cpp:814:8: warning: variable 'rt_size' set but not used [-Wunused-but-set-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:2270:11: warning: variable 'vp_height' set but not used [-Wunused-but-set-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:2673:22: warning: variable 'e' set but not used [-Wunused-but-set-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:715:7: warning: variable 'no_cull' set but not used [-Wunused-but-set-variable]
drivers/gles2/shader_gles2.cpp:693:14: warning: variable 'cc' set but not used [-Wunused-but-set-variable]
drivers/gles3/rasterizer_canvas_gles3.cpp:1226:8: warning: variable 'rt_size' set but not used [-Wunused-but-set-variable]
drivers/gles3/rasterizer_scene_gles3.cpp:3039:10: warning: variable 'contrib' set but not used [-Wunused-but-set-variable]
drivers/gles3/rasterizer_scene_gles3.cpp:4504:32: warning: variable 'vp_height' set but not used [-Wunused-but-set-variable]
editor/editor_inspector.cpp:272:9: warning: variable 'guide_color' set but not used [-Wunused-but-set-variable]
editor/editor_themes.cpp:1067:14: warning: variable 'alpha3' set but not used [-Wunused-but-set-variable]
editor/editor_themes.cpp:263:8: warning: variable 'script_bg_color' set but not used [-Wunused-but-set-variable]
editor/plugins/collision_shape_2d_editor_plugin.cpp:326:11: warning: variable 'cpoint' set but not used [-Wunused-but-set-variable]
editor/plugins/mesh_editor_plugin.cpp:72:9: warning: variable 'size' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:471:12: warning: variable 'mpos' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:89:8: warning: variable 'basetype_color' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:90:8: warning: variable 'type_color' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:92:8: warning: variable 'string_color' set but not used [-Wunused-but-set-variable]
modules/visual_script/visual_script_editor.cpp:2521:7: warning: variable 'seq_connect' set but not used [-Wunused-but-set-variable]
platform/android/export/export.cpp:580:12: warning: variable 'styles_count' set but not used [-Wunused-but-set-variable]
platform/android/export/export.cpp:584:12: warning: variable 'styles_offset' set but not used [-Wunused-but-set-variable]
platform/osx/export/export.cpp:464:9: warning: variable 'zerr' set but not used [-Wunused-but-set-variable]
scene/2d/tile_map.cpp:260:10: warning: variable 'tcenter' set but not used [-Wunused-but-set-variable]
scene/3d/light.cpp:166:7: warning: variable 'editor_ok' set but not used [-Wunused-but-set-variable]
scene/3d/navigation.cpp:566:11: warning: variable 'closest_navmesh' set but not used [-Wunused-but-set-variable]
scene/gui/rich_text_label.cpp:869:8: warning: variable 'size' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:705:14: warning: variable 'xform' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:706:8: warning: variable 'ss' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:726:14: warning: variable 'xform' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:727:8: warning: variable 'ss' set but not used [-Wunused-but-set-variable]
scene/resources/material.cpp:430:7: warning: variable 'using_world' set but not used [-Wunused-but-set-variable]
servers/visual/shader_language.cpp:2026:7: warning: variable 'all_const' set but not used [-Wunused-but-set-variable]
servers/visual/visual_server_scene.cpp:1383:28: warning: variable 'z_max_cam' set but not used [-Wunused-but-set-variable]
```
Also fixes two [-Wunused-value] warnings:
```
scene/gui/text_edit.cpp:4405:20: warning: statement has no effect [-Wunused-value]
servers/visual/visual_server_scene.cpp:905:48: warning: value computed is not used [-Wunused-value]
```
Some of those are bugs and need further work, they are identified with
`// FIXME` comments.
Also turn off -Wsign-compare warnings in the future, we do not consider them important.
Fixes the following GCC 5 warnings:
```
core/node_path.cpp:279:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
core/oa_hash_map.h:169:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
core/oa_hash_map.h:314:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
drivers/gles2/shader_gles2.cpp:985:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
drivers/gles3/rasterizer_storage_gles3.cpp:1075:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
drivers/pulseaudio/audio_driver_pulseaudio.cpp:343:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
editor/editor_plugin.cpp:525:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
editor/editor_properties_array_dict.cpp:747:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
editor/plugins/spatial_editor_plugin.cpp:2078:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
editor/plugins/spatial_editor_plugin.cpp:4096:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
editor/plugins/sprite_editor_plugin.cpp💯20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/cvtt/image_compress_cvtt.cpp:122:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/cvtt/image_compress_cvtt.cpp:134:77: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/cvtt/image_compress_cvtt.cpp:339:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/etc/image_etc.cpp:222:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/gdnative/register_types.cpp:242:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/gdnative/register_types.cpp:258:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/opensimplex/simplex_noise.cpp:200:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/opensimplex/simplex_noise.cpp:222:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
modules/opensimplex/simplex_noise.cpp:246:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/android/export/export.cpp:1085:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/android/export/export.cpp:1489:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/android/export/export.cpp:1623:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/iphone/export/export.cpp:206:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/iphone/export/export.cpp:356:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/iphone/export/export.cpp:406:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
platform/iphone/export/export.cpp:493:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/3d/audio_stream_player_3d.cpp:420:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/resources/audio_stream_sample.cpp:565:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/resources/audio_stream_sample.cpp:571:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
servers/audio/audio_rb_resampler.cpp:156:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
```
The following warnings were not fixed, as they implied casting for no gain:
```
core/io/packet_peer.cpp:228:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
core/io/resource_format_binary.cpp:109:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
drivers/gles2/rasterizer_scene_gles2.cpp:144:57: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
drivers/unix/file_access_unix.cpp:249:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/3d/voxel_light_baker.cpp:889:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/3d/voxel_light_baker.cpp:1020:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/3d/voxel_light_baker.cpp:1154:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/3d/voxel_light_baker.cpp:2255:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
scene/resources/bit_mask.cpp:336:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
servers/audio/audio_stream.cpp:141:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
servers/audio/audio_stream.cpp:150:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
servers/audio/audio_stream.cpp:154:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
servers/audio_server.cpp:86:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
servers/audio_server.cpp:89:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
```
Fixes the following GCC 5 warnings:
```
core/io/resource_format_binary.cpp:1721:29: warning: suggest parentheses around arithmetic in operand of '|' [-Wparentheses]
core/typedefs.h:108:24: warning: suggest parentheses around comparison in operand of '!=' [-Wparentheses]
editor/plugins/spatial_editor_plugin.cpp:2202:58: warning: suggest parentheses around comparison in operand of '!=' [-Wparentheses]
editor/plugins/spatial_editor_plugin.cpp:5002:12: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
main/input_default.cpp:346:59: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
main/input_default.cpp:348:60: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
main/input_default.cpp:579:57: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
modules/gridmap/grid_map_editor_plugin.cpp:613:14: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
modules/theora/video_stream_theora.cpp:335:34: warning: suggest parentheses around '+' in operand of '&' [-Wparentheses]
modules/theora/video_stream_theora.cpp:336:35: warning: suggest parentheses around '+' in operand of '&' [-Wparentheses]
modules/visual_script/visual_script_property_selector.cpp:215:38: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
scene/gui/rich_text_label.cpp:424:84: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
scene/gui/rich_text_label.cpp:512:80: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
scene/gui/scroll_container.cpp:173:36: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
scene/gui/scroll_container.cpp:173:86: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
scene/gui/tree.cpp:1419:98: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
```
Better heuristic for the shortest path algorithm for navigation2D and navigation.
It now will use the shortest distance to the polygon as cost instead of the distance to the center.
SimplexNoise can be used to generate parameterized fractal noise based on Open Simplex.
NoiseTexture uses SimplexNoise to generate noise textures for using in
shaders/visual effects.
