Fix getshiftedlevelzeroindex method
Change the method signature. Better consideration of the HTG 1D and 2D case excluding XY. Extend the vtkRandomHyperTreeGridSource test to ensure the sustainability of this fix.
Change the method signature. Better consideration of the HTG 1D and 2D case excluding XY. Extend the vtkRandomHyperTreeGridSource test to ensure the sustainability of this fix.