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/Map/Submarine.cs

@@ -895,14 +895,20 @@ namespace Barotrauma
             return sub;            
         }
 
+        public static bool Unloading
+        {
+            get;
+            private set;
+        }
+
         public static void Unload()
         {
+            Unloading = true;
 
             Sound.OnGameEnd();
 
             if (GameMain.LightManager != null) GameMain.LightManager.ClearLights();
 
-
             foreach (Submarine sub in loaded)
             {
                 sub.Remove();
@@ -919,6 +925,8 @@ namespace Barotrauma
             Ragdoll.list.Clear();
 
             GameMain.World.Clear();
+
+            Unloading = false;
         }
 
         public override void Remove()