Added support for CullVisitor to contain a osg::State. This used when

cull Callbacks require the contextID for  doing operations on texture
objects, for example.  Modified CullVisitor SceneView and Drawable

src/osgUtil/CullVisitor.cpp

@@ -257,7 +257,7 @@ void CullVisitor::apply(Geode& node)
 
         if( drawable->getCullCallback() )
         {
-            if( drawable->getCullCallback()->cull( this, drawable ) == true )
+            if( drawable->getCullCallback()->cull( this, drawable, _state.valid()?_state.get():NULL ) == true )
             continue;
         }
         else

src/osgUtil/SceneView.cpp

@@ -369,6 +369,8 @@ void SceneView::cullStage(osg::Matrix* projection,osg::Matrix* modelview,osgUtil
     cullVisitor->setRenderGraph(rendergraph);
     cullVisitor->setRenderStage(renderStage);
 
+    cullVisitor->setState( _state.get() );
+
     renderStage->reset();
 
     // comment out reset of rendergraph since clean is more efficient.