ENH: VTK6 migration, removal of GetProducerPort().

1)Removal of GetProducerPort() from vtkDataObject.
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Removal_of_GetProducerPort
ENH: VTK6 migration, removal of VTK 4 Backwards Compatibility Superclasses.

Removal of VTK 4 Backwards Compatibility Superclasses.
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Overview#Removal_of_Data_Objects.E2.80.99_Dependency_on_the_Pipeline
http://www.vtk.org/Wiki/VTK/Tutorials/New_Pipeline#Converting_an_Existing_Filter_to_the_New_Pipeline