buglist: cutting Shopkeeper the long worm

Cutting a shopkeeper poly'd as a long worm would generate strange messages
and could result in a crash.  cutworm didn't deal with all the intricacies
of duplicating a monster.   Fixed by changing cutworm() to use clone_mon()
to do most of its dirty work.  It seems to me that without this change,
cutting a tame long worm could also have similar bad effects.
Other side effects of this change:
- clone_mon now takes x,y coordinates, 0,0 results in previous behavior
- clone_mon no longer always makes cloned monsters tame/peaceful if player
  caused the clone, using the same formula previously in cutworm.  Someone
  else may wish to tweak this for gremlins.
- clone_mon will christen the new mon with the old shopkeeper's name, even
  though clones are never shopkeepers (game can't handle 2 for a shop)
- cutworm can now be called during conflict or pet combat, although I
  added no such calls (yet)

doc/fixes34.3

@@ -66,6 +66,8 @@ avoid traveling into water/lava, using usual running rules
 unchanging iron golem would still rehumanize in a rust trap
 fix an impossible rndmonst: bad `mndx' bug
 pets should not try to go after objects that they can't reach
+cutting a shopkeeper polymorphed in to a long worm would generate strange
+	messages and could cause a crash
 
 
 Platform- and/or Interface-Specific Fixes