Tons of AI + pathfinding bugfixes:

- waypoints are created between docked subs and removed when they undock
- fixed start waypoint being left out of steering paths
- NPCs won't close doors/hatches on themselves
- NPCs won't let go of ladders until their feet are above the lower edge of the hull
- fixed FindDivingGear "loops": need to find a suit -> need to get to a suit -> need a suit to get to the suit -> need to find a suit...
- fixed characters constantly turning from side to side in small rooms
- recursive function for finding the button which opens a door (so a button doesn't have to be connected straight to a door for an NPC to be able to open it)
- AIObjectiveGetItem keeps searching for more suitable items even if a path to a matching item has been found

Subsurface/Source/Characters/BackgroundSprite/BackgroundCreature.cs

@@ -42,6 +42,11 @@ namespace Barotrauma
             get { return FarseerPhysics.ConvertUnits.ToSimUnits(position); }
         }
 
+        public Vector2 WorldPosition
+        {
+            get { return position; }
+        }
+
         public Vector2 Velocity
         {
             get { return new Vector2(velocity.X, velocity.Y); }