Fix problem when really old elements are added to a new project. These elements do not have an uuid for each terminal. So when exporting, save an unique ID into the terminal. So the conductors know to which terminal they must be connected

sources/diagram.h

@@ -257,6 +257,13 @@ class Diagram : public QGraphicsScene
 					   NumerotationContext *nc);
 		void changeZValue(QET::DepthOption option);
 
+		/*!
+		 * \brief uniqueTerminalID
+		 * Determines a new unique Terminal ID
+		 * This is used only for legacy purpose
+		 */
+        int uniqueTerminalID() const;
+
 	public slots:
 		void adjustSceneRect ();
 		void titleChanged(const QString &);