Make the engine compatible with my crappy netbook which only has OpenGL 2.1 / GLSL 1.2 support.
+ Use degenerate triangle strips for text instead of the flat method
+ Use GL_ALPHA8 for 8bit textures if texture_rg isn't supported
+ Add texture swizzle func to allow a single shader to work with both GL_ALPHA and GL_RED textures
+ Use GLSL 1.2 if functionality from later versions isn't required.