Purge a lot of really old and obsolete documents, and merge some together
where possible. Lots of efnet docs and the old ircd-ratbox manpage (lol)
was purged.

Reorganise everything nice and neatly as possible. Things describing
features can be found in features/, and some more technical documents
were moved to techinical/.

Old credits file was consolidated into credits-past.txt, and a reference
was added to it in the credits.