Make a copy of the input material mesh (ClipMethod) to prevent crash when dealing with PointsData
requested to merge 33-fix-crash-when-applying-vtkmaterialinterface-filter-with-points-variables-regression into main
By bisecting the git commit i has been found that the crash mentioned in #33 (closed) was due to the deletion of the copy of the input mesh. This MR reintroduces a copy of the input mesh for the ClipMethod class. An explanation (a bit obscur) may be found in the vtkClipDataSet algorithm.
This MR also adds a test to ensure the filter do not crash anymore when Points data are present.
Closes #33 (closed)