Refactored Zone to new system

src/engine/objects/Zone.java

@@ -215,6 +215,9 @@ public class Zone extends AbstractWorldObject {
 
         this.parent = ZoneManager.getZoneByUUID(parentZoneID);
 
+        if (parent != null)
+            parent.addNode(this);
+
         // Seafloor
 
         if (ZoneManager.seaFloor.equals(this)) {