Renamed IDimDoor.placeDimDoor() to placeLink(), since that's what it's
actually being used for in our doors. Saying it places the door itself
is confusing.
Merged together the different changes we had made to Transdimensional
Trapdoors. Cleaned up the rendering and tile entity code a bit, it
should be a little more understandable now.
Got the Transdimensional Trapdoor working again. Renamed the file to
TransTrapdoor and trimmed off unnecessary code - BlockTrapDoor
implements a lot of the necessary logic. Implemented IDimDoor for
clarity.