Read first command-line argument as config file

[calebbraun]

Running Xanthos from the command line requires the first (only) argument to be the configuration file:

python xanthos/model.py example/pm_abcd_mrtm.ini

This errors because the flag -config_file was not specified. We should assume any extra argument is the -config_file parameter.

[rplzzz]

If that's the intended use, then why not just drop the - in this line?

xanthos/xanthos/model.py

Line 133 in 44dbf9b

parser.add_argument('-config_file', type=str, help='Full path with file name to INI configuration file.')

That should make the configuration file a positional rather than flag-type argument.

[crvernon]

We could do this for the current setup, but the goal was to get users used to the behavior incase we ever extended the args.

[rplzzz]

I think the best practice is usually to make mandatory arguments positional, while flags are mostly optional arguments.

[crvernon]

Ok, that sounds reasonable.