Fix the export of GmfSets in the case of multiple source models
Merge pull request #1417 from gem/fix-gmfset-export

Fix the export of GmfSets in the case of multiple source models
Changed the _do_run_calc signature
Merge branch 'run-calc' into getter-builder
Added a method EventLoss.to_csv_str
Restored the usual task_arg_gen