Removed Obsolete Code from PocketManager

Removed obsolete code from PocketManager. Much of that functionality has
already been reimplemented in other classes.
Reorganized and Renamed Classes

Moved tile entity classes to a separate package. Renamed some block
classes to match their in-game names (e.g. ChaosDoor -> UnstableDoor).
Moved TransientDoor to the blocks package. Cleaned up a little bit of
the code and automatically updated references to the classes that were
modified.