Branch off an OpenGL 3 backend from the current OpenGL 4 backend

[aconstlink]

As new features are introduced, it would make sense to branch of to a OpenGL 3 backend implementation because right now, most of the code is GL 3 compatible and might get lost in the process of OpenGL 4 advancement!

Along with that, motor needs gen3 objects.

Also make sure to share as much OpenGL code as possible among OpenGL 4, OpenGL 3 and OpenGL Es3! Otherwise the amount of code could get out of hand and would lead to an absolute divergence when new engine features are implemented and need testing!