Refactored Zone to new system

src/engine/objects/Zone.java

@@ -50,7 +50,7 @@ public class Zone extends AbstractWorldObject {
     public int min_level;
     public int max_level;
     public boolean hasBeenHotzone = false;
-    public ArrayList<Zone> nodes = null;
+    public ArrayList<Zone> nodes = new ArrayList<>();
     public int parentZoneID;
     public Zone parent = null;
     public Bounds bounds;