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.