When a player types something, and it's not an '@' command, exits are
checked to see if they match what the player typed. Exits don't have to
be in the same room as the player any longer.

Order of exit matching:
a. Exits attached to the players location, that aren't EXTERNAL.
b. EXTERNAL exits carried by the player.
c. EXTERNAL exits attached to objects (not players) in the player's location.
d. If the player's location isn't a room, the root parent room (usually #0)
   is checked for matching exits. If they are in a room, it's parent is
   checked, and then the parent of that, etc., all the way back to the root
   room.

Note that any exits that are matched in a group will override any (potential)
matches in the next group(s).