Improve the commandline argument support.
* --compose accepts a comma separated list of recipients.
* --attach can add multiple attachments, separator is ;;
(Better suggestions for separator are always welcome)
* both arguments can be used multiple times.

Example: mailody --compose 1@lnix.net --attach "/foo/bar;;/foo/baz" --compose 1@mailody.net,2@mailody.net
This will open a composer with /foo/bar and /foo/baz attached.
Recipients will be 1@lnix.net, 1@mailody.net and 2@mailody.net