This is a full optparse-based parser for all the options we want
to have in Ophis 2.0, but the pass-disablers aren't working yet.
This also doesn't handle positional arguments the way we hope
to eventually; that will come later.
optparse is deprecated in 2.7, but its replacement isn't available
in any previous version of Python, so we avoid it so as to not
gratuitously break compatibility on older machines.
It would be nice to at least stay usable on stock Leopard Macs (2.5).