still more Master Key of Thievery

Make #untrap while carrying the non-cursed (for rogues) or blessed
(for non-rogues) Key work the same as #invoke has been doing (without
regard to its bless/curse state):  when used on trapped door or chest,
that trap will always be found and disarming it will always succeed.

It should work when carried by monsters too:  if they try to open a
trapped door while carrying the Key (must be blessed since they're
not rogues) the trap will be automatically disarmed.  (Caveat:  that
hasn't been adequately tested.)

TODO (maybe...):  change the #invoke property to detect unseen/secret
door detection instead of #untrap.  The latter isn't completely
redundant; it works when the Key is cursed.  But quest artifacts
strongly resist becoming cursed so that isn't a particularly useful
distinction.

Also, trap hints when wielding the Key without gloves didn't notice
adjacent door and chest traps.  Now it does.  And the behavior is
slightly different:  known traps covered by objects or monsters are
treated like unknown traps as far as the hot/cold hints go.

src/monmove.c

@@ -1246,6 +1246,16 @@ postmov:
                 boolean btrapped = (here->doormask & D_TRAPPED) != 0,
                         observeit = canseeit && canspotmon(mtmp);
 
+                /* if mon has MKoT, disarm door trap; no message given */
+                if (btrapped && has_magic_key(mtmp)) {
+                    /* BUG: this lets a vampire or blob or a doorbuster
+                       holding the Key disarm the trap even though it isn't
+                       using that Key when squeezing under or smashing the
+                       door.  Not significant enough to worry about; perhaps
+                       the Key's magic is more powerful for monsters? */
+                    here->doormask &= ~D_TRAPPED;
+                    btrapped = FALSE;
+                }
                 if ((here->doormask & (D_LOCKED | D_CLOSED)) != 0
                     && (amorphous(ptr)
                         || (can_fog(mtmp)