Currently, traveling through a disconnected portal will just drop you out on the other side with no way of getting back to where you came from. There should be a config setting that makes it so that traveling through a disconnected portal will generate a portal on the opposite side for the player to use to get back to the original portal.

This is especially important because this update makes some major changes to how portal locations and connectivity work meaning that most portals in existing world will get disconnected.

There is a circumstance where attempting to travel through a portal will yield no output locations at all. In this case the input portal should just break or play a sound or something.

This is related to #7.