Made AudioFrame and Vector2 equivalent for casting. Added ability to obtain the playback object from stream players. Added ability to obtain effect instance from audio server.
Also drop some unused files. Renamed: - `scene/2d/navigation2d.h` -> `navigation_2d.h` - `scene/2d/screen_button.h` -> `touch_screen_button.h` - `scene/3d/scenario_fx.h` -> `world_environment.h` - `scene/audio/audio_player.h` -> `audio_stream_player.h` - `scene/resources/bit_mask.h` -> `bit_map.h` - `scene/resources/color_ramp.h` -> `gradient.h` - `scene/resources/shape_line_2d.h` -> `line_shape_2d.h` - `scene/resources/scene_format_text.h` -> `resource_format_text.h` - `scene/resources/sky_box.h` -> `sky.h` Dropped: - `scene/resources/bounds.h`
