Removed dependency of the new osg::DOFTransform and osg::Sequence Node's

on osgUtil by implementing a NodeVisitor::VisitorType enum, and associated
g/setVisitorType.  This allows callbacks to querry the visitor/traversal
type without doing down cast's to specific visitor subclasses such as
osgUtil::AppVisitor/CullVisitor.

src/osgUtil/CullVisitor.cpp

@@ -75,7 +75,7 @@ class PrintVisitor : public NodeVisitor
 };
 
 CullVisitor::CullVisitor():
-    NodeVisitor(NodeVisitor::TRAVERSE_ACTIVE_CHILDREN),
+    NodeVisitor(CULL_VISITOR,TRAVERSE_ACTIVE_CHILDREN),
     _currentRenderGraph(NULL),
     _currentRenderBin(NULL),
     _computeNearFar(COMPUTE_NEAR_FAR_USING_BOUNDING_VOLUMES),