by extension, require its presence to cause doors to be 3d
for consistency with the appearance/style of mtg doors in worlds that
wouldn't normally use the 3d extras mod
minor rework of closet door textures to make them work decently in both modes
more efficient use of texture space, fewer polys, less wasted vertices.
also made it and empty bookshelf use default wood where possible, and
composite the inside-back texture from overlay + default wood.
