Major changes:
* Stop overwriting object origins; this is needed so that everything will
properly rotate around the X axis.
* Improved method of storing vertex color and UV values, theoretically allowing
for more than five of color maps or UV maps to be read. Both are stored in
dictionaries to avoid hard-coding limits.
* Duplicate UV coordinates are made unique; this allows for things like some
assist fighters' eyes to be properly textured.
* Add new UI option to allow importing black vertex colors; they are not
imported by default as they can cause meshes to become too difficult to see.