digging holes

If you manage to escape a hole and then dig down with a pick-axe at
that location, finish on the first move instead of after the usual N turns.

doc/fixes34.4

@@ -92,6 +92,7 @@ monkeys can't steal rings worn under cursed weapon
 succubi will remove hero's gloves before taking worn ring; incubi will do
 	so before forcing ring to be put on
 mbodypart should return forehoof, not foreclaw, for horselike monsters
+further digging of an existing hole finishes in a single turn
 
 
 Platform- and/or Interface-Specific Fixes