Fixes the following Clang 7 warnings:
```
core/object.cpp:44:1: warning: '_ObjectDebugLock' defined as a struct here but previously declared as a class [-Wmismatched-tags]
core/variant_call.cpp:43:1: warning: '_VariantCall' defined as a struct here but previously declared as a class [-Wmismatched-tags]
drivers/gles3/rasterizer_storage_gles3.h:765:2: warning: 'MultiMesh' defined as a struct here but previously declared as a class [-Wmismatched-tags]
editor/editor_node.h:794:1: warning: 'EditorProgress' defined as a struct here but previously declared as a class [-Wmismatched-tags]
modules/bullet/rigid_body_bullet.h:230:17: warning: class 'KinematicUtilities' was previously declared as a struct [-Wmismatched-tags]
modules/bullet/space_bullet.h:60:1: warning: class 'btSoftBodyWorldInfo' was previously declared as a struct [-Wmismatched-tags]
scene/resources/world_2d.cpp:40:1: warning: 'SpatialIndexer2D' defined as a struct here but previously declared as a class [-Wmismatched-tags]
scene/resources/world.cpp:39:1: warning: 'SpatialIndexer' defined as a struct here but previously declared as a class [-Wmismatched-tags]
servers/audio/reverb_sw.cpp:60:1: warning: 'ReverbParamsSW' defined as a struct here but previously declared as a class [-Wmismatched-tags]
thirdparty/bullet/BulletSoftBody/btSoftBody.h:43:1: warning: 'btSoftBodyWorldInfo' defined as a struct here but previously declared as a class [-Wmismatched-tags]
```
Fixes the following GCC 5 warnings:
```
core/object.h:193:11: warning: 'MethodInfo::flags' will be initialized after [-Wreorder]
core/object.h:192:15: warning: 'PropertyInfo MethodInfo::return_val' [-Wreorder]
core/object.cpp:278:1: warning: when initialized here [-Wreorder]
core/script_debugger_remote.h:97:6: warning: 'ScriptDebuggerRemote::max_cps' will be initialized after [-Wreorder]
core/script_debugger_remote.h:91:6: warning: 'int ScriptDebuggerRemote::max_messages_per_frame' [-Wreorder]
core/script_debugger_remote.cpp:1086:1: warning: when initialized here [-Wreorder]
core/script_debugger_remote.h:98:6: warning: 'ScriptDebuggerRemote::char_count' will be initialized after [-Wreorder]
core/script_debugger_remote.h:92:6: warning: 'int ScriptDebuggerRemote::n_messages_dropped' [-Wreorder]
core/script_debugger_remote.cpp:1086:1: warning: when initialized here [-Wreorder]
modules/bullet/area_bullet.h:102:7: warning: 'AreaBullet::isScratched' will be initialized after [-Wreorder]
modules/bullet/area_bullet.h:92:39: warning: 'PhysicsServer::AreaSpaceOverrideMode AreaBullet::spOv_mode' [-Wreorder]
modules/bullet/area_bullet.cpp:46:1: warning: when initialized here [-Wreorder]
modules/bullet/collision_object_bullet.h:127:15: warning: 'CollisionObjectBullet::space' will be initialized after [-Wreorder]
modules/bullet/collision_object_bullet.h:117:7: warning: 'CollisionObjectBullet::Type CollisionObjectBullet::type' [-Wreorder]
modules/bullet/collision_object_bullet.cpp:67:1: warning: when initialized here [-Wreorder]
modules/bullet/godot_ray_world_algorithm.h:48:7: warning: 'GodotRayWorldAlgorithm::m_ownManifol1d' will be initialized after [-Wreorder]
modules/bullet/godot_ray_world_algorithm.h:46:33: warning: 'const btDiscreteDynamicsWorld* GodotRayWorldAlgorithm::m_world' [-Wreorder]
modules/bullet/godot_ray_world_algorithm.cpp:50:1: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:91:18: warning: 'GodotAllConvexResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:89:6: warning: 'int GodotAllConvexResultCallback::m_resultMax' [-Wreorder]
modules/bullet/godot_result_callbacks.h:93:2: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:142:18: warning: 'GodotAllContactResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:140:6: warning: 'int GodotAllContactResultCallback::m_resultMax' [-Wreorder]
modules/bullet/godot_result_callbacks.h:147:2: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:168:18: warning: 'GodotContactPairContactResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:166:6: warning: 'int GodotContactPairContactResultCallback::m_resultMax' [-Wreorder]
modules/bullet/godot_result_callbacks.h:173:2: warning: when initialized here [-Wreorder]
modules/bullet/godot_result_callbacks.h:195:18: warning: 'GodotRestInfoContactResultCallback::m_exclude' will be initialized after [-Wreorder]
modules/bullet/godot_result_callbacks.h:191:7: warning: 'bool GodotRestInfoContactResultCallback::m_collided' [-Wreorder]
modules/bullet/godot_result_callbacks.h:199:2: warning: when initialized here [-Wreorder]
modules/bullet/rigid_body_bullet.h:200:9: warning: 'RigidBodyBullet::gravity_scale' will be initialized after [-Wreorder]
modules/bullet/rigid_body_bullet.h:199:9: warning: 'real_t RigidBodyBullet::mass' [-Wreorder]
modules/bullet/rigid_body_bullet.cpp:258:1: warning: when initialized here [-Wreorder]
modules/bullet/rigid_body_bullet.h:222:28: warning: 'RigidBodyBullet::force_integration_callback' will be initialized after [-Wreorder]
modules/bullet/rigid_body_bullet.h:219:7: warning: 'bool RigidBodyBullet::isTransformChanged' [-Wreorder]
modules/bullet/rigid_body_bullet.cpp:258:1: warning: when initialized here [-Wreorder]
modules/bullet/rigid_body_bullet.h:220:7: warning: 'RigidBodyBullet::previousActiveState' will be initialized after [-Wreorder]
modules/bullet/rigid_body_bullet.h:208:6: warning: 'int RigidBodyBullet::maxCollisionsDetection' [-Wreorder]
modules/bullet/rigid_body_bullet.cpp:258:1: warning: when initialized here [-Wreorder]
modules/bullet/soft_body_bullet.h:69:9: warning: 'SoftBodyBullet::total_mass' will be initialized after [-Wreorder]
modules/bullet/soft_body_bullet.h:68:6: warning: 'int SoftBodyBullet::simulation_precision' [-Wreorder]
modules/bullet/soft_body_bullet.cpp:38:1: warning: when initialized here [-Wreorder]
modules/bullet/soft_body_bullet.h:76:9: warning: 'SoftBodyBullet::drag_coefficient' will be initialized after [-Wreorder]
modules/bullet/soft_body_bullet.h:61:14: warning: 'btSoftBody* SoftBodyBullet::bt_soft_body' [-Wreorder]
modules/bullet/soft_body_bullet.cpp:38:1: warning: when initialized here [-Wreorder]
modules/bullet/space_bullet.h:97:22: warning: 'SpaceBullet::solver' will be initialized after [-Wreorder]
modules/bullet/space_bullet.h:95:35: warning: 'btDefaultCollisionConfiguration* SpaceBullet::collisionConfiguration' [-Wreorder]
modules/bullet/space_bullet.cpp:333:1: warning: when initialized here [-Wreorder]
modules/bullet/space_bullet.h:101:23: warning: 'SpaceBullet::soft_body_world_info' will be initialized after [-Wreorder]
modules/bullet/space_bullet.h:99:23: warning: 'btGhostPairCallback* SpaceBullet::ghostPairCallback' [-Wreorder]
modules/bullet/space_bullet.cpp:333:1: warning: when initialized here [-Wreorder]
modules/gdnative/nativescript/nativescript.h:79:13: warning: 'NativeScriptDesc::base_native_type' will be initialized after [-Wreorder]
modules/gdnative/nativescript/nativescript.h:73:9: warning: 'String NativeScriptDesc::documentation' [-Wreorder]
modules/gdnative/nativescript/nativescript.h:88:9: warning: when initialized here [-Wreorder]
modules/gdscript/gdscript.h:296:6: warning: 'GDScriptWarning::line' will be initialized after [-Wreorder]
modules/gdscript/gdscript.h:294:4: warning: 'GDScriptWarning::Code GDScriptWarning::code' [-Wreorder]
modules/gdscript/gdscript.h:303:2: warning: when initialized here [-Wreorder]
scene/3d/physics_body.h:544:7: warning: 'PhysicalBone::simulate_physics' will be initialized after [-Wreorder]
scene/3d/physics_body.h:543:7: warning: 'bool PhysicalBone::_internal_static_body' [-Wreorder]
scene/3d/physics_body.cpp:2502:1: warning: when initialized here [-Wreorder]
scene/3d/physics_body.h:546:6: warning: 'PhysicalBone::bone_id' will be initialized after [-Wreorder]
scene/3d/physics_body.h:539:12: warning: 'Skeleton* PhysicalBone::parent_skeleton' [-Wreorder]
scene/3d/physics_body.cpp:2502:1: warning: when initialized here [-Wreorder]
scene/3d/spring_arm.h:44:11: warning: 'SpringArm::mask' will be initialized after [-Wreorder]
scene/3d/spring_arm.h:43:8: warning: 'float SpringArm::current_spring_length' [-Wreorder]
scene/3d/spring_arm.cpp:37:1: warning: when initialized here [-Wreorder]
scene/animation/skeleton_ik.h:159:11: warning: 'SkeletonIK::target_node_override' will be initialized after [-Wreorder]
scene/animation/skeleton_ik.h:152:7: warning: 'bool SkeletonIK::use_magnet' [-Wreorder]
scene/animation/skeleton_ik.cpp:418:1: warning: when initialized here [-Wreorder]
scene/resources/tile_set.h:84:9: warning: 'TileSet::AutotileData::size' will be initialized after [-Wreorder]
scene/resources/tile_set.h:83:7: warning: 'int TileSet::AutotileData::spacing' [-Wreorder]
scene/resources/tile_set.h:92:12: warning: when initialized here [-Wreorder]
scene/resources/tile_set.h:115:12: warning: 'TileSet::TileData::tile_mode' will be initialized after [-Wreorder]
scene/resources/tile_set.h:114:9: warning: 'Color TileSet::TileData::modulate' [-Wreorder]
scene/resources/tile_set.h:120:12: warning: when initialized here [-Wreorder]
servers/physics/body_sw.h:84:19: warning: 'BodySW::direct_state_query_list' will be initialized after [-Wreorder]
servers/physics/body_sw.h:57:11: warning: 'uint16_t BodySW::locked_axis' [-Wreorder]
servers/physics/body_sw.cpp:756:1: warning: when initialized here [-Wreorder]
```
Nothing really relevant for us, but it's not a bad consistency
improvement anyway so worth taking.
Fixes GCC 5 warnings of the form:
core/io/http_client.cpp:288:9: warning: enumeration value 'STATUS_SSL_HANDSHAKE_ERROR' not handled in switch [-Wswitch]
core/io/marshalls.cpp:806:9: warning: enumeration value 'AABB' not handled in switch [-Wswitch]
Those can be trivial cases where adding a default fallback is the solution,
or more complex issues/hidden bugs where missed values are actually meant
to be handled.
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
```
This allows more consistency in the manner we include core headers,
where previously there would be a mix of absolute, relative and
include path-dependent includes.
The margin value is exposed into the UI for shape ressource.
This value can be modified through set_margin and get from get_margin
or by using the property margin. Each time the margin is modified
the associated collision shape is recreated and the margin value is
used in ShapeBullet::prepare.
