Provide at least a basic description of every package we build. Where
possible, the description is taken from a relevant manpage; when there
was no suitable text in the manpage, I wrote a new description.
Since the UCL files now contain a significant amount of English
prose which is almost certainly subject to copyright in at least
some jurisdictions, add a copyright header to every file. Where
the text was taken from a manpage, the copyright and license are
also taken from the manpage. A few files don't have copyright
headers added because the origin of the text is unclear, or because
the files were written by someone else.
Remove some orphaned UCL files for packages we no longer ship, and
while here, add a few missing dependencies.