Slope textures

[Travis Cobbs]

I agree that if something like this were done, all lines should begin with !MATERIAL (or something similar; the point being, only introduce ONE new meta-command). In fact, I think !MATERIAL should require one of the following three sub-commands as the first word after !MATERIAL: BEGIN, END, and NEXT. The NEXT sub-command would mean that the material specification applies to the next line only. BEGIN and END produce a block of lines using a material.

Additionally, just as an aside, the spelling for the non-shiny finish is matte, not mat.