Allow to bind data vars (eg X,Y..) to the 3D objects (width, color...)

This is an important widget.
It will allow users to *freely* assign a parameters found in the graph model (eg. label, x, y, any other parameter...) to variables describing the scene (eg node.z, node.visibility, node.width, node.color...)
Of course one will be able to bind variables to python methods as well (ex to calculate things, via something like "addToSum(node.value)")

It may be interesting too to embed the graph nodes inside python objects.