Fix monster trapped state being wrong

When cloning a monster, clear the clone trapped and hiding states.
When splitting a monster (eg. a black pudding), the clone could
be placed on a trap, so do mintrap.
When removing a monster from the map, clear the trapped state.

src/makemon.c

@@ -842,6 +842,8 @@ xchar x, y; /* clone's preferred location or 0 (near mon) */
     m2->mx = mm.x;
     m2->my = mm.y;
 
+    m2->mundetected = 0;
+    m2->mtrapped = 0;
     m2->mcloned = 1;
     m2->minvent = (struct obj *) 0; /* objects don't clone */
     m2->mleashed = FALSE;

src/mhitm.c

@@ -419,7 +419,8 @@ register struct monst *magr, *mdef;
                                  || objects[otmp->otyp].oc_material == METAL))
                     && mdef->mhp > 1
                     && !mdef->mcan) {
-                    if (clone_mon(mdef, 0, 0)) {
+                    struct monst *mclone;
+                    if ((mclone = clone_mon(mdef, 0, 0)) != 0) {
                         if (vis && canspotmon(mdef)) {
                             char buf[BUFSZ];
 
@@ -427,6 +428,7 @@ register struct monst *magr, *mdef;
                             pline("%s divides as %s hits it!", buf,
                                   mon_nam(magr));
                         }
+                        mintrap(mclone);
                     }
                 }
             } else

src/mon.c

@@ -1687,6 +1687,7 @@ struct monst **monst_list; /* &migrating_mons or &mydogs or null */
     }
 
     if (on_map) {
+        mon->mtrapped = 0;
         if (mon->wormno)
             remove_worm(mon);
         else

src/uhitm.c

@@ -1227,7 +1227,8 @@ int dieroll;
             /* but not bashing with darts, arrows or ya */
             && !(is_ammo(obj) || is_missile(obj)))
         && hand_to_hand) {
-        if (clone_mon(mon, 0, 0)) {
+        struct monst *mclone;
+        if ((mclone = clone_mon(mon, 0, 0)) != 0) {
             char withwhat[BUFSZ];
 
             withwhat[0] = '\0';
@@ -1235,6 +1236,7 @@ int dieroll;
                 Sprintf(withwhat, " with %s", yname(obj));
             pline("%s divides as you hit it%s!", Monnam(mon), withwhat);
             hittxt = TRUE;
+            mintrap(mclone);
         }
     }