This commit implements a big update of rlgl module, intended to optimize some parts. This change could break some code bases... hopefully not, but it could.
The BIG changes to the module are:
 - Replaced LINES-TRIANGLES-QUADS buffers by a single one, now all vertex data is accumulated on a single buffer and managed with registered draw calls. LINES-TRIANGLES-QUADS could be used the same way as before, rlgl will manage them carefully. That's a big improvement of the system.
 - Support multi-buffering if required. Just define MAX_BATCH_BUFFERING desired size (currently set to 1 batch). Should be enough for most of the situations.
 - Removed temporal accumulative buffers for matrix transformations, now transformations are directly applied to vertex when on rlVertex3f()
 - Reviewed rlPushMatrix()/rlPopMatrix() to be consistent with OpenGL 1.1, probably I should remove that ancient behaviour but... well, it was not consistent and now it is.
 - Minor tweaks: LoadText(), I broke it in last update... also multiple comments reviewed.
 - TODO: MAX_BATCH_ELEMENTS checking should probably be reviewed... done some tests and it works but...

- Renamed Begin3dMode() --> BeginMode3D()
- Renamed Begin2dMode() --> BeginMode2D()
- Renamed End3dMode() --> EndMode3D()
- Renamed End2dMode() --> EndMode2D()

Examples have been renamed for coherence with raylib modules and test
examples have been merged into examples folder.

Check CHANGELOG for the list of changes in this release!

View CHANGELOG for details