Migliorato il save e restore counter in modo da funzionare anche se ci sono bug o crash

it/unisa/info13d/Utility/IdCounter.java

@@ -16,7 +16,7 @@ public class IdCounter {
 
     public static void save_counter() throws  FileNotFoundException,IOException,ClassNotFoundException{
         File f_data = new File("id_counter");
-        Integer data = Integer.valueOf(Global.get_next_id() - 1);
+        Integer data = Integer.valueOf(Global.getGeneral_counter());
         ObjectOutputStream writer = new ObjectOutputStream(new FileOutputStream(f_data));
         writer.writeObject(data);
         writer.close();