--Changed BlockRift to use ITileEntityProvider instead of BlockContainer
--Reorganized some of the code in TileEntityRift to improve performance
and readability
Cleaned up the code in TileEntityRift. Fixed up some spacing and changed
as many functions and fields to private as possible. Added a performance
improvement by doing the random roll for Enderman spawning before
searching for nearby Endermen.
Changed rifts to using world.destroyBlock() instead of
world.setBlockToAir(). That has the advantage of causing block
destruction animations and sound effects instead of blocks vanishing
silently.
