I created these classes on Feb 08, 2005 and they are showing their age.
The following changes will update them to be more VTK 6 compliant and
 easier to use in ParaView.

 Changes:
    1) Setting names for the scalar, normals and texture coordinate arrays.
        Thereby enabling easier usage in ParaView.
    2) Used vtkSmartPointer where appropriate.
    3) Removed BTX/ETX for the enum, in vtkParametricFunctionSource.h
    3) Prevent out of bounds errors by using vtkSetClampMacro where appropriate.
    4) Updated documentation, changing links and credits where appropriate.

Change-Id: I136e443d57ff4479843f48fc6eb8540475e8f8e2
Signed-off-by: Andrew Maclean <andrew.amaclean@gmail.com>