Add the snapping feature to the TMTK pipeline

[Distantz]

Many of us TMTK creators make modular sets, the ability to use the ingame snaps would make the process of building using tmtk a lot more manageable. A possible way to implement this would to use specially named Empty objects, which like the LODs, could have a special prefix. I doubt this would cause many issues and most creators would be conservative with it, so I see it as a worthy feature to be included.