implementato nodeposition con to string e reverse. aggiunto copyright

deque/utility/DLNode.java

@@ -6,6 +6,9 @@ package deque.utility;
  * Date: 17/03/14
  * Time: 16:32
  */
+
+//Copyright (c) 2003 Brown University, Providence, RI
+//Additional modifications and methods by xgiovio
 public class DLNode <E> {
 
     public DLNode (){