It directly uses the libraries provided by the system

Note this new raygui version embeds ricons and `GuiTextBoxMulti()` is not working properly

Now rlgl uses the `Matrix` type, just make sure it has been previously defined somewhere... I don't like this approach but it's probably the easier one for the users... still looking for a better solution... maybe using something like
`#define MATRIX_TYPE`, so it can be checked in other modules.

rlgl has been redesigned to avoid any dependency to `raylib` or `raymath`, all functions using some of those libs have been reviewed.
 - REMOVED: `Texture2D`, `Shader` structs dependency
 - REMOVED: `Vector3`, `Matrix` structs dependency
 - REMOVED: raymath functions dependency, all required math is implemented in rlgl
 - ADDED: `rlMatrix` custom rlgl type
 - ADDED: `utils.c`: `rlMatrixFromMatrix()` and `rlMatrixToMatrix()` for a safe conversion between raylib<->rlgl matrix types
 - ADDED: `rl` prefix to all `rlgl` structs
 - Other small tweaks here and there

* Added an example for raylib OpenGL interop.

* Removed C99 variable-length array to fix MSVC errors

* Moved the opengl interop example from shaders to others.

* Fixing typecast warnings generated by visual studio 2019 in examples.

* Changes to fixes based on feedback

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>

Without GLFW_OPENGL_FORWARD_COMPAT, running this as a standalone will yield the error:
```
NSGL: The targeted version of macOS only supports forward-compatible core profile contexts for OpenGL 3.2 and above
```

Stumbled on this example and I love this! Adding instructions that work for me on MacOS.. Note that glfw3 will need to be statically built locally and copied to this external/libs directory on mac. I can upload my static version, but it probably makes sense to do this only if there's some general naming convention for adding platform specific folders. Like "external_osx/lib" or "external/lib_osx". Then I'll drop my static libs in there.

See #1304

* Update year of copyright notices

* Fix mistake in comment

* Fix typo ("algorythms")

* Replace tabs with spaces

* Remove trailing whitespace and fix mistake in comment

* Fix ExportImageAsCode missing comment rectangle corner

* Replace tab with spaces

* Replace tabs with spaces

Already integrated into raylib

Multiple functions added and some reviewed to adapt to the new multi-mesh, multi-material and animated models.

Planning to promote raudio module as a simple and easy-to-use front-end for the amazing mini_al library, so the name change.

Name comes from raylib-audio but in spanish it also remembers to word "raudo", meaning  "very fast", an analogy that fits perfectly to the usefulness and performance of the library!

Consequently, raylib version has been bumped to 2.4-dev.