Usefult to draw rectangles using default font texture

Exposed some raymath useful functions to raylib API

Moved PBR material loading to example, right decision?

...to avoid possible conflicting symbols

Namely:
- GenImageHorizontalV
- GenImageHorizontalH
- GenImageChecked
- GenImageWhiteNoise
- GenImageCellular

The gradient implementation may be a bit naive, for example it doesn't do any gamma correction.

useful when using FLAG_WINDOW_RESIZABLE.

LoadSpriteFontTTF() --> LoadSpriteFontEx()

enum LogType could require some revision...

Replaced old GetExtension() function
Make IsFileExtension() public to the API

Moved to custom example, now raylib only supports simulated VR
rendering.
Oculus code was too device dependant... waiting for OpenXR.

Supports line thickness

It seems Sleep() behaves weird on my computer, disabled by default
returning to the busy wait loop... also re-implemented DrawFPS() to
avoid frame blitting...

- SetWindowPosition(int x, int y);
- SetWindowMonitor(int monitor);

Working in modules configuration flags...

Also reviewed issue with stdbool when compiling with clang

Useful to set number of repeats for a music, needs to be tested...

Only DESKTOP platforms (Windows, Linus, OSX)

Now it uses CharInfo data, this way, it's better aligned with the future
RRES file format data layout for sprite font characters.

Preparing for next version... still some work left... :P

Now program is halted (OS signal call) for required amount of time every
frame, so CPU usage drops to zero, instead of using a busy wait loop.

Lighting is implemented as a raylib example now