Resolve "Save last state of MC run even if there is no data container filename specified"
requested to merge 256-save-last-state-of-mc-run-even-if-there-is-no-data-container-filename-specified into master
Just few changes here:
DataContainer._write has been made private while BaseEnsemble.write_data_container is public.
In this way, we ensure that last_state is effectively updated whenever you write your DataContainer to file.