pipermail to rss

This script turns a pipermail mailman archive into rss feeds.  It is derived from
http://jmason.org/software/scripts/mailman-archive-to-rss.txt from http://taint.org/mmrss/.  I've made a bit of a mess but nothing too serious.  The primary changes are that it can

1. process more than one archive at a time
2. output rss 1.0 and 2.0
   
3. process local archives from the filesystem rather than using http

Here it is.