Remove old "char *" casts from Python wrappers.

Wrapping/PythonCore/PyVTKClass.cxx

Wrapping/PythonCore/PyVTKMutableObject.cxx

Wrapping/PythonCore/PyVTKNamespace.cxx

Wrapping/PythonCore/PyVTKObject.cxx

Wrapping/PythonCore/PyVTKSpecialObject.cxx

Wrapping/PythonCore/PyVTKTemplate.cxx

Wrapping/PythonCore/vtkPythonArgs.cxx

Wrapping/PythonCore/vtkPythonCommand.cxx

Wrapping/PythonCore/vtkPythonUtil.cxx

Wrapping/Tools/vtkWrapPythonEnum.c

Wrapping/Tools/vtkWrapPythonInit.c

Wrapping/Tools/vtkWrapPythonMethodDef.c

Wrapping/Tools/vtkWrapPythonOverload.c

Wrapping/Tools/vtkWrapPythonType.c