argparse ConfigureAction problem

[Jason Friedman]

> ./plot_stuff2.py --plot stuff1 stuff2
> [...]
> plot_stuff2.py: error: argument --plot/--with-plot/--enable-plot/--no-plot/--
> without-plot/--disable-plot: invalid boolean value: 'stuff1'
>
> Problem is --plot takes an optional argument, and so the positional arg is
> assumed to be the arg to --plot.  Not sure how to fix this.

Maybe have a look at nargs='*' in
http://docs.python.org/py3k/library/argparse.html#nargs.