Make sure no memory leaks

src/engine/gameManager/BuildingManager.java

@@ -334,12 +334,25 @@ public enum BuildingManager {
             NPC hirelingNPC = (NPC) hireling;
 
             if (ForgeManager.vendorWorkOrderLookup.get(hirelingNPC) != null)
+
                 for (WorkOrder workOrder : ForgeManager.vendorWorkOrderLookup.get(hirelingNPC)) {
                     workOrder.runCompleted.set(true);
                     workOrder.vendor = null;
+
+                    // Remove any cooking items from collections
+                    // to ensure we don't leak memory.
+
+                    for (Item item : workOrder.cooking)
+                        ForgeManager.itemWorkOrderLookup.remove(item);
+
                     DbManager.WarehouseQueries.DELETE_WORKORDER(workOrder);
                 }
+
+            // Finally remove the NPC from ForgeManager
+
+            ForgeManager.vendorWorkOrderLookup.remove(hirelingNPC);
         }
+
         // Remove hireling from building
 
         building.getHirelings().remove(hireling);