Merged Robert's pull request for Graphics Systems Cleanup.

From pull request:

"Cleaned up the graphics systems file names to what Josh want's them as. Also moved all
texture functions to GLtextures.cpp/.h where they belong for my rewrite of the underlying
texture system, before we rewrite the whole graphics system for VBO's. Go ahead and pull when ready."

A minor merge conflict involving d3d_draw_{cone,ellipsoid} was handled
and tested to work correctly.