[TextureAtlas] Refactoring of bpy.ops.mesh uv textures.

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/contrib@4578 96b784f8-4ae3-dd11-aff7-0030488c597c
[TextureAtlas] refactoring again.

git-svn-id: https://svn.blender.org/svnroot/bf-extensions/contrib@4579 96b784f8-4ae3-dd11-aff7-0030488c597c