Continued clean up of the Doomsday public API; specifically graphics/drawing related stuff:
Removed DGL_Color and DGL_Color2 and instead exported GL_PalIdxToRGB. The renderer should not be worrying about palettes so call GL_PalIdxToRGB to do the conversion and use the result with e.g. DGL_Color3f
Removed GL_SetSprite, instead use GL_SetMaterial.
Removed GL_DrawPSprite and moved the drawing code (back?) into the game's HUD drawing routine(s). Also fixed an issue with the creation of material_ts for ddtexture_ts during startup.
Also fixed an issue with the creation of material_ts for ddtexture_ts during startup.