[vtkusers] Class-libraries mapping

[David Doria]

> Usually in vtk the library you need is the name of the folder that the
> source is in prepended with vtk.
>
>  For example if the class you want is in VTK-5.6.1\Hybrid
>
> then you link with vtkHybrid
>
> John

With recent versions of VTK, the preferred method is to link to ${VTK_LIBRARIES}

David