Adding and wrapping a custom namespace within VTK

[agirault (Alexis Girault)]

@dgobbi

I don’t see a compelling reason for vtkAnatomicalOrientation and vtkAnatomicalOrientation::CoordinateSystem to be separate entities.

Agreed, I actually mentionned that above. The only issue I then see is that I can’t define LPS anymore.

Also, I suppose I won’t be able to use custom constructors either?