Fix: concurrent access in Upper and Lower List, added img cache

src/main/java/it/polimi/ingsw/gc14/View/IView.java

@@ -7,6 +7,7 @@ import it.polimi.ingsw.gc14.Network.NetworkEvent;
 public interface IView {
     public void setModel(MiniModel miniModel);
     public void render();
+    public void applyAndRender(NetworkEvent event);
     public void showMessage(String message);
     public void showError(String message);