ENH: VTK6 migration, replacement of SetInput().

Replacement of SetInput() with SetInputData() and SetInputConnection().
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Replacement_of_SetInput.
ENH: VTK6 migration, changes to scalars and extent manipulation.

Changes to Scalars Manipulation Functions.
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Changes_to_Scalars_Manipulation_Functions.
http://vtk.org/Wiki/VTK/VTK6/Migration/WikiExamples#Improve.

Removal of SetWholeExtent and update extent methods
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Removal_of_SetWholeExtent
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Removal_of_Methods_for_Manipulating_Update_Extent