Use Entity.teleportTo for cross-world teleportation in CraftEntity

A previous attempt to use Entity.teleportTo was unconditional. This was
causing non-fatal errors to be thrown for cases when certain entities
were teleported within the same world. Entity.teleportTo *is* the
correct approach for cross-world teleports, so we can choose to use it
only in those cases.

Testing included using my Nethrar plugin for cross-world teleportation, and giving myself an ocelot pet via taming and then flying around, making sure the ocelot teleported to me, and seeing no log messages.