fix #Q117 - vomiting by rodents & more

From a bug report:  you could vomit when polymorphed into a rat but real life
rats can't/don't vomit.  The latter was confirmed by <Someone> and <Someone>.
While testing a fix for this, I discovered a couple of other problems.
Healing magic which cured sickness failed to heal Vomiting (potion or
spell; unicorn horn deals with them separately).  Enlightenment failed to
report Vomiting (it's not shown on the status line).  Most significant was
that vomiting_dialogue() called vomit() twice (also make_confused() and
make_stunned() three times for every once intended).  It was dividing the
remaining turns by 3 and then using that value to decide what to do, but
only message display took into account that the same divided value would
occur on 3 consecutive turns (or just 2 for the final countdown to 0,
because dialog routine gets called before timed-property decrement).

src/mondata.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)mondata.c	3.5	2006/11/24	*/
+/*	SCCS Id: @(#)mondata.c	3.5	2007/02/05	*/
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -335,6 +335,19 @@ sticks(ptr)	/* creature sticks other creatures it hits */
 		attacktype(ptr,AT_HUGS)));
 }
 
+boolean
+cantvomit(ptr)
+struct permonst *ptr;
+{
+    /* rats and mice are incapable of vomitting;
+       which other creatures have the same limitation? */
+    if (ptr->mlet == S_RODENT &&
+	    ptr != &mons[PM_ROCK_MOLE] &&
+	    ptr != &mons[PM_WOODCHUCK])
+	return TRUE;
+    return FALSE;
+}
+
 /* number of horns this type of monster has on its head */
 int
 num_horns(ptr)