TINYGL: Moved a few external C functions inside ZBuffer.
TINYGL: Moved all external C functions inside the struct ZBuffer.
TINYGL: Refactored zTriangleFill texture access code.
TINYGL: Added assert to ensure correct texture format.
TINYGL: Refactored fill functions inside ZBuffer struct.
TINYGL: Renamed ZBuffer into FrameBuffer
TINYGL: Refactored the name of FrameBuffer instance from zb to fb
TINYGL: Refactored the triangle function in a template fashion
TINYGL: Refactored shadow drawing routines
TINYGL: Removed all the macros from triangle draw routines.
TINYGL: Refactored line drawing routines.
TINYGL: Removed unnecessary files and updated changelog.
Merge branch 'master' into buffer-refactoring-squashed

Conflicts:
	engines/grim/gfx_tinygl.cpp
	graphics/tinygl/Changelog