* OpenGLES 2.0 support on PLATFORM_DESKTOP

* exmples raylib_opengl_interop desktop GLES2 support

* rename gles2.h -> glad_gles2.h

* add GLTF animation support

* use correct index when allocating animVertices and animNormals

* early exit LoadModelAnimationsGLTF if the gtlf file fails to parse

* update models/models_loading_gltf.c to play gltf animation

Updated the .blend file to use weights rather than bone parents so it
fits into the framework. Exported with weights to the .glb file.

* fix order of operations for bone scale in UpdateModelAnimation

* minor doc cleanup and improvements

* fix formatting

* fix float formatting

* fix brace alignment and replace asserts with log messages

WARNING: It could require further review of `GamepadThread()` function where `js_event gamepadEvent.number` detecting current pressed button could generate a missmatch with index 0 (reserved for button unknow). Or maybe `0` could just be `GAMEPAD_BUTTON_NONE`? In that case, consistency with other inputs should be carefully considered...

* Update year to 2023

* Update raylib.h year to 2023

* Fix vector2angle

* Fix ;

* use acosf

* need a break

* add comments

With this fix the function still returns negative values, which is
wrong. But we keep this behaviour to maintain backwards compatibility.

It would try to use the glfw on the system but we're cross-compiling for web where the implementation is provided by emscripten's team

* Updated rcore.c, renamed 'time' to 'time_nsec'

When PLATFORM_ANDROID, PLATFORM_RPI or PLATFORM_DRM were defined, there is a compilation error to redefinition of the variable 'time', so the second instance of 'time' was changed to 'time_nsec' which both fixes the name collision and more accurately describes what that variable represents.

* Renamed 'time_nsec' to 'nanoSeconds'

This breaks other values of the struct.

* Use const for pointer float array

* missed a definition

Reviewed formating to follow raylib coding conventions.

rlCullFace sets the face culling mode to RL_FRONT or RL_BACK which correspond to GL_FRONT and GL_BACK respectively.

Added a comment explaining the range limitations of GetRandomValue.
Added a run-time warning TRACELOG when GetRandomValue is called with an invalid range.

Those two functions have been moved to a new example: `models_draw_cube_texture`. The reasons for this decision:
 - Function inflexibility: Many users with the need to draw a textured cube could need to customize the texture applied to every face, that function did not allow that kind of functionality.
 - rlgl functionality exposure: The implementation exposed will teach users how to implement custom textured triangles drawing.

This function implementation has been moved to the related example. Current implementation can be probably customized depending on user needs.

This function can be easely replicated using `DrawtexturePro()` and actually it was doing some assumptions not transparent to the user. Even the function name was confusing. No example was available for it and actually noone requested one example.

Function moved to `examples/textures/textures_polygon.c`, so users can learn from the implementation and create custom variants as required.

Co-authored-by: nobytesgiven <nobytesgiven@users.noreply.github.com>