Small NNTP server for leaf sites

 sn is a small news system for small sites serving perhaps a few
 dozen newsgroups, and with a slow connection to the internet.
 It is similar to leafnode (ftp.troll.no, by Arnt Gulbrandsen).
 The target user is a home or SOHO with a single modem connection
 to the Internet, maybe running IP masq or similar, and serving a
 few workstations.