Adding the beginnings of the OpenGL code, sans drawing for the time being.
Added GL drawing cache, made framebuffers work right.
Added a great dela of support to OpenGL draw functions.
Added DrawRectGraph behavior and misc comments.
Fixed a number of rendering related bugs.
Made type conversions explicit.
Added support for DrawLine thickness.
Corrected blending behavior, settings reset behavior.
Correctly bind the framebuffer on startup and resize.
Added support for Windows build of OpenGL version.
First pass of OpenGL blending modes.
Merge branch 'opengl' of https://github.com/mauvecow/DxPortLib into opengl

Conflicts:
	src/OpenGL_Draw.c
Merge pull request #1 from mauvecow/opengl

OpenGL Support.