Merge topic 'VTK-Fix_XMLWriter_polyhedron_appended_mode'

61d9f7ae Removed a spurious white line
e665230b Reverted vtkXMLPolyDataWriter.cxx to use the 'old' WriteCellsAppended method
7a99bbb1 Merge branch 'VTK-Fix_XMLWriter_polyhedron_appended_mode' of https://gitlab.kitware.com/mennodeij1/vtk

 into HEAD
d6a3449a VTK: Fixed XML problem when writing grids with VTK_POLYHEDRON cell types

Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Andrew Bauer <andy.bauer@kitware.com>
Merge-request: !501