Fixed formatting error in BukkitEntity.
Changed Location to use Extents rather than worlds and overhauled the new Entity code a bit.
Added new Extent-compatible Clipboard and BlockArrayClipboard classes.

The goal is to replace use of CuboidClipboard with these new classes.

Support for entities, //flip, //rotate, and //distr still needs to be
re-implemented.

DataException was also removed from BaseBlock because The Base(...)
classes should be "dumb" blocks without any validation.
Fixed RepeatingExtentPattern repeating a (1, 1, 1) smaller region.