[Dune] Iteration over parallel grid

[Martin Rückl]

Hi "Duners",
I want to iterate over all vertices (or elements) of a parallel grid in 
the following way:
Each vertex should be accessed only once, not only for each rank, but 
for the whole set of parallel processes.
In other words, suppose there is a (boundary/overlap) vertex shared by 
the two ranks r0 and r1, then only r0 OR r1 should iterate over it.

Is this possible for vertices with the GridView iterators selecting a 
certain partition_iterator type? YES/NO ?

I think for elements it should be possible, if the grid does not use 
overlap. Correct/Wrong?

Thanks,
Martin