converting SCORR to CORR unblocks vision

- fix several cases where a point was unblocked by unblock_point wasn't
 called, directly or indirectly

src/apply.c

@@ -278,6 +278,7 @@ use_stethoscope(obj)
 	case SCORR:
 		You_hear(hollow_str, "passage");
 		lev->typ = CORR;
+		unblock_point(rx,ry);
 		if (Blind) feel_location(rx,ry);
 		else newsym(rx,ry);
 		return res;

src/detect.c

@@ -1046,10 +1046,12 @@ genericptr_t num;
 		    levl[zx][zy].doormask = D_NODOOR;
 		} else
 		    levl[zx][zy].doormask = D_ISOPEN;
+		unblock_point(zx, zy);
 		newsym(zx, zy);
 		(*(int*)num)++;
 	} else if(levl[zx][zy].typ == SCORR) {
 		levl[zx][zy].typ = CORR;
+		unblock_point(zx, zy);
 		newsym(zx, zy);
 		(*(int*)num)++;
 	} else if ((ttmp = t_at(zx, zy)) != 0) {

src/music.c

@@ -338,6 +338,7 @@ do_pit:		    chasm = maketrap(x,y,PIT);
 		    if (*in_rooms(x, y, SHOPBASE))
 			add_damage(x, y, 0L);
 		    levl[x][y].doormask = D_NODOOR;
+		    unblock_point(x,y);
 		    newsym(x,y);
 		    break;
 	    }

src/trap.c

@@ -1314,6 +1314,7 @@ int style;
 			if (cansee(bhitpos.x, bhitpos.y))
 				pline_The("boulder crashes through a door.");
 			levl[bhitpos.x][bhitpos.y].doormask = D_BROKEN;
+			if (dist) unblock_point(bhitpos.x, bhitpos.y);
 		}
 	}
 	tmp_at(DISP_END, 0);