[vtkusers] cleaning vtkSilhouette result

[David Doria]

nsarrasin,

Thank you very much for adding an example!

http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/ExternalContour

This is the best way to prevent the duplication of effort by future
users, thanks! Next time it may be a good idea to send an announcement
that you have done so so that if someone finds this email thread, they
will be able to follow it to your example.

David