TINYGL: Added a few utility functions in TinyGL
MYST3: Added tinyGL renderer.
MYST3: Implemented 2D rendering correctly.
MYST3: Implemented selection between hardware and software rendering.

Conflicts:
	engines/myst3/gfx_opengl.cpp
MYST3: Fixed incorrect viewport issues.
MYST3: Added openGL shader renderer selection.
MYST3: Fixed a memory leak issue in tinyGL renderer texture.
MYST3: Added a note in the code.
MYST3: Removed dependency to GLU
TINYGL: Updated makefile and changelog.

Conflicts:
	graphics/tinygl/Changelog
TINYGL: Added comments to code
TINYGL: Added comments to code
MYST3: Removed dependency on openGL
TINYGL: Implemented tglDepthMask.
MYST3: Fixed an error with 2D non textured rect rendering.
Merge pull request #940 from subr3v/myst3-renderer

MYST3: TinyGL Renderer