[WIP] 3D Textures

Implementation of 3D textures using PyOpenGL.
Looks like the `master` you rebased off of is too old to have that functionality, too (string support for color names). When you said this still happens when you merge latest master, is that true even after you do `git fetch upstream && git rebase upstream/master`? I have a feeling you're merging in an old version of master. But given the difficulty with this, I can just fix it after merge.