[vtkusers] Memory leak in VTK-Python module

[Pierre Barbier de Reuille]

Hello,

I am using VTK from Python, and I noticed that I need to explicitly
unregister the objects once for Python to actually free it. One thing I
didn't find out though is if I needed to explicitly handle the memory of
my VTK objects from Python or if the object should be implicitly kept
alive as long as I hold a reference on it.

Thanks,

Pierre