Graphics System Textures *Merge*
Renamed texture_get_pixwidth and height to texture_get_texel_width to
match Studio, and also added texture_set_stage for binding multitextures.
Please merge when ready.
Whoops, removing include I accidentally left from Josh having me test
something.
Merge pull request #312 from RobertBColton/master

Graphics System Textures *Merge*