vtkDIYDataExchanger: compatibility with other data types

Hi everyone,

The function vtkDIYDataExchanger::AllToAll is very useful as it significantly eases data communication between MPI processes as it implements MPI_AllToAllv with very easy to use interface (it automatically computes the recvCounts array).

However, it lacks support for datatypes different from vtkDataSet, I suppose that this is due to issues with the serialization process of other classes. This issue can be seen in the filter vtkOverlappingCellsDetector which has some DIY boilerplate code to exchange Bounding Boxes between MPI processors which could be avoided if one adds support for other datatypes to vtkDIYDataExchanger::AllToAll.

I have tried to rewrite the same function vtkDIYDataExchanger::AllToAll for other objects such as vtkDataArray but I quickly run into errors.

I am willing to add support through MR for datatypes different from vtkDataSet to vtkDIYDataExchanger::AllToAll, however I would appreciate if anyone could give me any insight if the current serialization capabilities of VTK and DIY allow to do so?

Thank you