This commit adds a new (hidden) debugging option,
DebugEmitCellPartition (--debug-emit-cell-partition)
which, when set, will cause each rank to write a three-column text
file of the form
MPI_Rank Cartesian_Index NLDD_Domain_ID
into the directory
partition/CaseName
of the run's output directory. That file will be named according to
the process' MPI rank, so the first column will be the same as the
file name.
The option is primarily intended for debugging the NLDD partitioning
scheme, so is mostly reserved for runs with low MPI sizes (e.g.,
less than 20).
While here, also make the MPIPartitionFromFile helper class aware of
this format so that we can use concatenated output files as an input
to the MPI partitioning algorithm for repeatability.
c0c96123bc