[Sorry for attached patch, but I fully expect my mailer to butcher it
otherwise.]

iw currently works, but the error handling is a bit off, many error
messages are absent, and the help text is flat-out wrong.  This
partially fixes the above and should make it possible for noobs to add
and remove interfaces without reading the entire source.

Signed-Off-By: Andy Lutomirski <luto@myrealbox.com>