Added ability to customize the keys used to control stats

include/osgViewer/StatsHandler

@@ -34,6 +34,12 @@ class StatsHandler : public osgGA::GUIEventHandler
             SCENE_STATS = 3,
             LAST = 4
         };
+        
+        void setKeyEventTogglesOnScreenStats(int key) { _keyEventTogglesOnScreenStats = key; }
+        int getKeyEventTogglesOnScreenStats() const { return _keyEventTogglesOnScreenStats; }
+        
+        void setKeyEventPrintsOutStats(int key) { _keyEventPrintsOutStats = key; }
+        int getKeyEventPrintsOutStats() const { return _keyEventPrintsOutStats; }
 
         bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa);
 
@@ -53,6 +59,9 @@ class StatsHandler : public osgGA::GUIEventHandler
 
         void setUpScene(osgViewer::Viewer* viewer);
 
+        int                             _keyEventTogglesOnScreenStats;
+        int                             _keyEventPrintsOutStats;
+
         int                             _statsType;
         osg::ref_ptr<osg::Camera>       _camera;
         osg::ref_ptr<osg::Switch>       _switch;