The problem with closing exits

[Tero Jyri Michael Pelander <tpeland@utu.fi>]

I have now found out one of the ways that bring the 'the exit is closed' bug
constantly.  When a player is moving to a _new_ (=unloaded) map and and other
player enters an exit the later player will get where he wanted to but the
player that initiated the load of new map is going to be stuck.  The loaded
map has all exits closed.  Even if the other player is comming to the same
map as the previous player they will get to different locations.  Only way
out of the 'stuck map' is  word of recall or invis_exit.  The later will return
to the real map (and even load it if needed) after he returns.

I don't know what to fix.  That is left for others.

(crossfire 0.90.4)