Skull 3 entrance fix - could be refined

Thieves Town region addition - couldn't reach certain doors from elsewhere.
Ice Palace trap doors and fixed a couple broken staircases

DoorShuffle.py

@@ -1548,8 +1548,8 @@ default_door_connections = [
     ('Skull 3 Lobby NW', 'Skull Star Pits SW'),
     ('Skull Vines NW', 'Skull Spike Corner SW'),
     ('Thieves Lobby E', 'Thieves Compass Room W'),
-    ('Thieves Ambush E', 'Thieves BK Corner W'),
-    ('Thieves BK Corner NW', 'Thieves Pot Alcove Bottom SW'),
+    ('Thieves Ambush E', 'Thieves Rail Ledge W'),
+    ('Thieves Rail Ledge NW', 'Thieves Pot Alcove Bottom SW'),
     ('Thieves BK Corner NE', 'Thieves Hallway SE'),
     ('Thieves Pot Alcove Mid WS', 'Thieves Spike Track ES'),
     ('Thieves Hellway NW', 'Thieves Spike Switch SW'),