Collect All Dbihar Patches in One Output Mesh

vtkEndPointsToDbiharFilter produces vtkPolyData output combining
all patches in one mesh. The filter uses internally the following
filters:

vtkStructuredGridGeometryFilter
vtkAppendPolyDataFilter
vtkCleanPolyDataFilter

This will have to be changed/adjusted in the future if the numbering
scheme of the cells in the output is to be made easier to follow.