start breaking save out from Mussa::analyze()

start breaking save out from Mussa::analyze()
This patch changes Mussa::save() to take a boost::filesystem::path
so we have some hope of saving to a specified location.

However so the application will continue to work while I go try
the boost::serialize path, I left the save() call in analyze(), so
it will continue to auto-save.

For this to work I'll need to add a save option to the gui and
remove the save call in analyze.

(Though I did leave the save() call in parse_option that will
force saving a run when launched from the command line.