Fixed DungeonSchematic

Modified DungeonSchematic to use the new link and dimension classes.
Fixed PocketBuilder and More

1. Changed DungeonSchematic to use an external instance of Random rather
than initializing its own.
2. Created the Pair class, a strongly-typed tuple that was needed in
PocketBuilder.
3. Added a missing calculation in NewDimData for setting the packDepth
field during dungeon initialization.
4. Finished code missing in PocketBuilder. Changes listed above were
needed for this.
More Progress on Rewrite

Continued fixing things across various classes to make them work with
our new core classes.
More Progress on Rewrite

Continued fixing things across various classes to make them work with
our new core classes. I've also cleaned up indentation and random code
snippets along the way.
More Progress on Rewrite

More cleaning up errors and code. There were a lot of things that needed
simplifying. Rather than fix the 3 or 5 copies of the same function
throughout the code, I made an effort to use the same function and
delete its copies.

Created the BaseItemDoor class to hold all the basic door item methods
that don't vary between types. That helped cut down on fixing things.
Also renamed the door item classes to match their in-game  names.

There is still a ton of duplicate code out there.
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.
Removed DimRail Files

Removed files related to DimRail since they seem to be left over from a
scrapped idea. We can revert this commit later to restore them.
More Progress on Rewrite

Fixed the code in ItemLinkSignature and ItemStabilizedRiftSignature.
Removed obsolete code from PocketManager - we don't need to worry about
storing link keys anymore. All the data is stored in NBT, which means no
more generating unique keys or worrying about saving and loading them.
Renamed ItemLinkSignature to ItemRiftSignature

Renamed ItemLinkSignature to ItemRiftSignature to match its in-game
name. Automatically updated references to the old class name.
More Progress on Rewrite

Fixed the code in DDTeleporter and made minor changes to other classes
that depended on those fixes. Ensured that PocketManager's load, save,
and unload methods are called appropriately and rewrote some of their
code. Made various changes in other classes (e.g. EventHookContainer,
PlayerRespawnTracker) to pass them references to DDProperties through
their constructors instead of having them rely on
DDProperties.instance() - this is a better programming practice in the
long run.

Renamed initialization methods in mod_pocketDim to make it clear that
they're called on events. Commented out command registration in
mod_pocketDim so that we can test DD as soon as PacketHandler is fixed,
without worrying about fixing the command classes.
Modified NewDimData and IDimLink

Modified how links are created so that the caller must specify a link
type when the link is created, rather than setting it later. This was
done to avoid having to send two link data packets following the way
links would be handled logically. Turns out this was good idea overall
for ensuring link integrity, because there was one case where I forgot
to set the link type after creating the link.
Started Rewriting Packet Handling

Started rewriting our packet handling code. Deleted PacketHandler in
favor of using sided (Server-, Client-) packet handlers to make it
easier to follow what's going on in our code. Added some event-based
handling of updates which greatly simplified signaling that data needs
to be sent, but it's not completely done yet.
Deleted PacketHandler

Forgot to commit this change before.
Merge pull request #79 from SenseiKiwi/rewrite

Rewrite