[Paraview] error using new reader

[John Biddiscombe (CSCS)]

Brad,

> This is a bug related to the change of a reader from subclassing off 
> of vtkSource to subclassing off of a different vtkAlgorithm subclass.  
> I've add it to my to-do list to fix.

Thanks, I've changed back to using the sources instead of algorithms and 
it is behaving a bit more predictably now.

cheers

JB
PS. If you want to explain what needs fixing I'll be happy to try it 
later in the week.