of objects which were transformed by multiple matrices at one time - this
cannot be handled in the flattening process (since we only have one piece
of geometry to transform). This visitor now handles this case by disabling
flattening of any objects and transforms associated in this way.
different types of optimization on the scene graph - state optimization,
flattening static transforms, combining LOD's and removing redundent groups.
The new Optimizer replaces the once seperate OptimizerStateVisitor.
