motd.nnrpd and motd.innd

[Julien ÉLIE]

Hi all,

> * renaming "motd.news" to "motd.nnrpd" (via innupgrade);
> * implementing LIST MOTD in innd, using "motd.innd";
> * updating samples + documentation.

All done.

Changes are:

* Advertise the COUNTS, DISTRIBUTIONS, MODERATORS, MOTD and SUBSCRIPTIONS
keywords in the LIST capability for nnrpd.  Compliance to RFC 6048.

* Implement the message of the day in innd, and advertise it in its LIST
capability.

* The motd.news file (previously used only by nnrpd) is renamed to motd.nnrpd
during the run of innupgrade.

* A new motd.innd file is created for innd.

* In the 501 error code for an unexpected third argument to a LIST command,
mention it is not necessarily a wildmat.

* Better wording for the 503 error code in response to LIST.

* Documentation update.

* Symbolic links are created for motd.innd.5 and motd.nnrpd.5 (pointing
to the legacy motd.news.5 man page).

-- 
Julien ÉLIE

« Un ami fidèle qui parle très bien votre langue et toutes
  les langues vivantes : le latin, le grec, le celte, etc. » (Astérix)