Moved rendering support into GraphisContext, osgViewer::Viewer/View, and

added frame stamp updating and update traversal to osgViewer::Scene/Viewer.

Updated osgcamera example to use new Viewer API calls instead of using local
rendering calls.

src/osgViewer/Scene.cpp

@@ -24,6 +24,7 @@ Scene::Scene():
     _frameStamp->setReferenceTime(0);
 
     _updateVisitor = new osgUtil::UpdateVisitor;
+    _updateVisitor->setFrameStamp(_frameStamp.get());
 
     _eventQueue = new osgGA::EventQueue;
     _eventQueue->setStartTick(_startTick);
@@ -111,6 +112,10 @@ void Scene::frameEventTraversal()
 
 void Scene::frameUpdateTraversal()
 {
+    if (!getSceneData()) return;
+    
+    getSceneData()->accept(*_updateVisitor);
+    
     if (_databasePager.valid())
     {    
         // tell the DatabasePager the frame number of that the scene graph is being actively used to render a frame
@@ -121,3 +126,6 @@ void Scene::frameUpdateTraversal()
     }
 }
 
+
+ 
+