The source project of this merge request has been removed.
applies GNU long option convention
As per https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html, POSIX recommends options with a single dash, and GNU recommends that long options use double dashes for clarity.
mmdPublish.py used the GNU convention, but the other scripts did not.
This commit updates mmd2bagit, mmdCreate and mmdShow to use the
GNU convention as well.