Change the osg::NodeVisitor::getLocalToWorldMatrix() /
getWorldToLocalMatrix() methods so it do not initilize the matrix being
passed to them, and assume the the users has already initiliazed them
appropriately, such as to take account of camera positions.
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.
