Have taken a few more steps towards support for view dependant transformations

by adding a ComputeTransformCallback to osg::Transform, and have now removed
the recently added AutoTransform since it is nolonger required.  Have also
updated CullVisitor to account for the new ways for tracking transformation
matrices in the scene.

src/osg/NodeVisitor.cpp

@@ -43,3 +43,13 @@ void NodeVisitor::setTraversalVisitor(NodeVisitor* nv)
     if (_traversalVisitor.valid()) _traversalMode = TRAVERSE_VISITOR;
     else _traversalMode = TRAVERSE_NONE;
 }
+
+const bool getLocalToWorldMatrix(Matrix& matrix, MatrixMode mode)
+{
+    return false;
+}
+
+const bool getWorldToLocalMatrix(Matrix& matrix, MatrixMode mode)
+{
+    return false;
+}