Non-shader textures

[bfops]

First off, we just want to apply a texture in a seamless way to the extracted mesh (this is a good read).

Next, we want to be able to UV map the texture appropriately so avoid stretching. GPU Gems 3 talks about that.

[bfops]

Polygons are always generated in sets of 4, and they fit together in quadrilaterals. The width and height are bounded above by 2*voxel_width. We can use this to naively flatten voxel textures into a 2D texture, by creating a texture that has max_width*max_height space for each voxel edge.

[bfops]

bca24129aec3a05352ea20b53847eb7a40c09839 and 3d41399dafbac475a8f631c6d4785cd3b9d280e2 add some better grass/dirt texturing.