Remove duplicate nodes from chombo coupling file

[corbett5]

Is your feature request related to a problem? Please describe. Duplicate (ghosted) nodes are output in the chombo coupling file.

Describe the solution you'd like No duplicate nodes.

The proposed solution is to create a nodal field that is the index of each node in the coupling file and then sync this field using the standard method. Then we can just pass this field to the hdf5_coupler (which will need some slight modifications).

[rrsettgast]

@corbett5 was this done?

[corbett5]

No.