Update on random map bug

[Peter Mardahl <peterm@tesla.EECS.Berkeley.EDU>]

I've made some progress on why the random maps were causing a bug.

The actual crash isn't due to a segfault exactly, it's due to
the program aborting itself when it sees a face which is out-of-range
on a map and tries to send the out-of-range face to a client.

I modified crossfire to use face 0 for an out-of-range face, and
I found that the crashes happen this way:

1)  A multi-square monster is placed in the map.
2)  The map is loaded into memory.
3)  The player enters the map.
4)  The multi-square monster is screwed up because the non-head elements
    don't have the proper images.
5)  If the un-updated multi-square monster is onscreen with the player,
    it will crash.


Comment:  As soon as the monster moves, this is all fixed.

So the problem now seems to be that I don't know how to properly
stick multi-square monsters into maps.

PeterM