added icon to plotter

source/RobotAPI/gui-plugins/SensorActorWidgetsPlugin/ArmarXPlotter/ArmarXPlotter.h

@@ -97,6 +97,10 @@ namespace armarx
         {
             return "Observers.Plotter";
         }
+        virtual QIcon getWidgetIcon() const
+        {
+            return QIcon("://icons/combo_chart.svg");
+        }
         void loadSettings(QSettings* settings);
         void saveSettings(QSettings* settings);
         //for AbstractFactoryMethod class