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/osg/NodeVisitor.cpp

@@ -6,6 +6,18 @@ using namespace osg;
 
 NodeVisitor::NodeVisitor(TraversalMode tm)
 {
+    _visitorType = NODE_VISITOR;
+    _traversalNumber = -1;
+
+    _traversalVisitor = NULL;
+    _traversalMode = tm;
+    _traversalMask = 0xffffffff;
+    _nodeMaskOverride = 0x0;
+}
+
+NodeVisitor::NodeVisitor(VisitorType type,TraversalMode tm)
+{
+    _visitorType = type;
     _traversalNumber = -1;
 
     _traversalVisitor = NULL;