ENH: ModelToModelDistance matches 3DMeshMetric format in vtk files when using VTK filter

-Scalar array is named "Distance" by the VTK filter "vtkDistancePolyDataFilter"
-Scalar array is renamed "Signed" if the computed is signed
-Scalar array is renamed "Absolute" if the computed distance is not signed
-An additional and constant field is added to the vtkPoyData and is called "Original"
Merge pull request #614 from fbudin69500/update-ModelToModelDistance

ENH: ModelToModelDistance matches 3DMeshMetric format in vtk files when ...