Work on multiple slot support

src/engine/loot/WorkOrder.java

@@ -28,6 +28,7 @@ public class WorkOrder implements Delayed {
     public int slots_used;
     public int total_to_produce;
     public int total_produced;
+    public int msg_size;
     public HashMap<mbEnums.ResourceType, Integer> production_cost = new HashMap<>();
     public HashMap<mbEnums.ResourceType, Integer> production_cost_total = new HashMap<>();
     public int templateID;