[vtkusers] Converting vtkMultiBlockDataSet into vtkDataObject

[Berk Geveci]

> The Berk's approach seems straightforward to write also multi block files
> but, I guess, It will not be abled to write files as single blocks (.vtu in
> my case). The key point here is that I can't use some ParaView's features
> since my data is being treated as multi block even when I have only one
> part.

Not true. The reader will write one .vtm file that points to one or
more .vtu files. You can always ignore the .vtm file and open the .vtu
files separately. By the way, you can do this exact same thing from
inside paraview. Simply save the EnSight file and then open the .vtu
files. If you are doing it in parallel, you have to write your own
.pvtu file (which should be pretty easy).

-berk

> >>> Berk: Just a comment regarding these new VTK's features:
>
> These new features are being designed over the old classes. I guess that
> It's a bit dangerous since there's a bunch of codes out there that will
> simply stop working with the newest VTK's versions. There should be a kind
> of vtkGenericMultBlockEnsightReader while the old vtkGenericEnsightReader is
> kept for backward compatibility. Just a thought...

Makes a lot of sense. Sorry for not having done this when we switched.
I assumed that multi-block support will mature way faster than it has.
If, by 3.4, we don't have everything supported for multi-block, I will
try to get this in.

-berk