more engraving sanity feedback

Delete engravings made in a breach of a shop's wall or of a vault's
wall or in the guard's temporary corridor when the wall is repaired
or the corridor removed.  If 'sanity_check' was On, those would
trigger impossible warning "engraving sanity: illegal surface (x)"
where x was the terrain type code for solid rock or relevant walls.

Adding del_engr_at() calls to the shop code was straightforward.
The vault code is very complicated and I'm not sure that all the
calls I added were actually necessary.

src/zap.c

@@ -3217,7 +3217,7 @@ zap_updown(struct obj *obj) /* wand or spell */
             case WAN_POLYMORPH:
             case SPE_POLYMORPH:
                 del_engr(e);
-                make_engr_at(x, y, random_engraving(buf), gm.moves, (coordxy) 0);
+                make_engr_at(x, y, random_engraving(buf), gm.moves, 0);
                 break;
             case WAN_CANCELLATION:
             case SPE_CANCELLATION: