mudpy

The previous BSD-like mudpy license has been replaced with the one used by the OpenBSD project. It’s modeled after the Internet Software Consortium’s, a two-clause BSD license removing language made unnecessary by the Berne convention. This new license is functionally identical to the old one, just more terse and openly recognized.

While I was at it, I made sure to correct the copyright dates on some of the files in the current release and add a copyright statement to any files previously lacking one.