theme room vampire fix

From a reddit thread:  a 'mausoleum' theme room picked a vampire for
its occupant and applied the wait-for-you strategy to it.  Hero's ESP
or monster detection showed a meditating vampire bat.  Change monster
creation by the special level loader (which also handles theme rooms)
to force such a creature into its normal vampire form.

That revealed an older bug which wouldn't have been exercized prior
to theme rooms:  a meditating vampire could and would shape change
without ceasing meditation.  Make it not shape change rather come out
of its trance.

src/mon.c

@@ -4476,7 +4476,7 @@ decide_to_shapeshift(struct monst *mon, int shiftflags)
         /* regular shapeshifter */
         if (!rn2(6))
             dochng = TRUE;
-    } else {
+    } else if (!(mon->mstrategy & STRAT_WAITFORU)) {
         /* The vampire has to be in good health (mhp) to maintain
          * its shifted form.
          *

src/sp_lev.c

@@ -2133,6 +2133,11 @@ create_monster(monster *m, struct mkroom *croom)
         }
         if (m->waiting) {
             mtmp->mstrategy |= STRAT_WAITFORU;
+            /* if this is a vampire that got created already shifted into
+               bat/fog/wolf form and the special level or theme room didn't
+               explicitly request that, shift back to vampire */
+            if (vampshifted(mtmp) && m->appear != M_AP_MONSTER)
+                (void) newcham(mtmp, &mons[mtmp->cham], NO_NC_FLAGS);
         }
         if (m->has_invent) {
             discard_minvent(mtmp, TRUE);