Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix typos, mostly s/ an / a / where appropriate and a few s/an/and/
Add FreeBSD Id tag where missing.

$Id$ -> $FreeBSD$

Add mid scripts. Mid is a tool which create a Message-ID database
for mailing lists.