ENH: VTK6 migration, replacement of SetInput().

Replacement of SetInput() with SetInputData() and SetInputConnection(), the same kind of functions include SetInput1(), SetInput2() and SetSource().
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Replacement_of_SetInput
ENH: VTK6 migration, removal of GetProducerPort().

1)Removal of GetProducerPort() from vtkDataObject.
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Removal_of_GetProducerPort