wet towel enhancements

Flesh out wet towels a bit:
1) wielding a wet towel--or a dry one which becomes wet--won't give a
   "you begin bashing with your wet towel" message when attacking;
2) if a formerly wet towel dries out completely while wielded, *do* give
   "you begin bashing with your towel" on the next attack;
3) successfully hitting with a wet towel no longer always loses wetness;
4) water damage to dry towel always confers at least 1 point of wetness;
5) taking fire damage (via burnarmor() which is used for most types of
   fire damage) has a chance to partially or fully dry a wet towel
   (regardless of whether it's wielded at the time; applies to monsters
   as well as hero; each towel being carried is checked until one is
   affected, then any others escape drying.

Not done:
-) attacking with a wielded wet towel perhaps ought to be treated as a
   weapon attack using whip skill rather than an augmented arbitrary-
   junk-by-weight attack;
-) throwing a wet towel should probably ignore wetness--it's just a wet
   piece of cloth when not finishing with a whip snap; right now, it
   loses a point of wetness when thrown and usually--#3 above--another
   point if it hits...;
-) hitting burning creatures is no different than hitting anything else;
-) likewise for hitting wet creatures.

include/extern.h

@@ -1,4 +1,4 @@
-/* NetHack 3.6	extern.h	$NHDT-Date: 1440120640 2015/08/21 01:30:40 $  $NHDT-Branch: master $:$NHDT-Revision: 1.506 $ */
+/* NetHack 3.6	extern.h	$NHDT-Date: 1445126411 2015/10/18 00:00:11 $  $NHDT-Branch: master $:$NHDT-Revision: 1.508 $ */
 /* Copyright (c) Steve Creps, 1988.				  */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -2574,6 +2574,8 @@ E void FDECL(mwepgone, (struct monst *));
 E int FDECL(mon_wield_item, (struct monst *));
 E int NDECL(abon);
 E int NDECL(dbon);
+E void FDECL(wet_a_towel, (struct obj *, int, BOOLEAN_P));
+E void FDECL(dry_a_towel, (struct obj *, int, BOOLEAN_P));
 E int NDECL(enhance_weapon_skill);
 E void FDECL(unrestrict_weapon_skill, (int));
 E void FDECL(use_skill, (int, int));