Made the osgGA::GUIEventHandler sublassed from osg::Object as a virtual

inheritence to allow handler to also be used as node callbacks.

Fix to UpdateVisitor to make the visitation of Drawable more consistent
with the way that nodes are traversed.

src/osgUtil/UpdateVisitor.cpp

@@ -15,7 +15,7 @@
 using namespace osg;
 using namespace osgUtil;
 
-UpdateVisitor::UpdateVisitor():NodeVisitor(UPDATE_VISITOR,TRAVERSE_ACTIVE_CHILDREN)
+UpdateVisitor::UpdateVisitor():NodeVisitor(UPDATE_VISITOR,TRAVERSE_ALL_CHILDREN)
 {
 }