Added Settings and Minor Preemptive Fix

Added a setting to DDProperties for controlling the max distance that
players can be moved randomly when they're sent to Limbo. We previously
had a setting for the same except for leaving Limbo. Cleaned up some of
the related code a little. Added another setting for the chance of rifts
dropping World Thread on block destruction. Also fixed a potential NPE
in EventHookContainer that could arise theoretically arise if a
non-Vanilla door was attached to a rift.