vtkMultiBlockDataSet equivalent for VTKHDF files

[mwestphal (Mathieu Westphal (Kitware))]

@lgivord

From the website we can download the .sha512 indeed, if we want directly the data it should be somewhere here I believe: https://www.paraview.org/files/, @mwestphal any inputs?

sha=`cat VTK/path/to/file.ext.sha512`
wget https://www.vtk.org/files/ExternalData/SHA512/$sha -O file.ext