Ghost cells generator: backend change
The ghost cells generator, which used to only work for vtkUnstructuredGrid, is now replaced by the new ghost cells generator that works on vtkImageData, vtkRectilinearGrid, vtkStructuredGrid, vtkUnstructuredGrid, and any vtkMultiBlockDataSet, vtkPartitionedDataSet, and vtkPartitionedDataSetCollection composed of the latter base types.
The old backend is being removed.