We are trying to simplify the logic in program `inst_eddies`. Also,
the program `inst_eddies` should not write `used_config_nml.txt` to
the top level of the SHPC directory since several instances could run
in parallel for several slices. So we are leaving it as a task for a
script over `inst_eddies` to create `used_config_nml.txt` at the top
level of the SHPC directory.