deal with rejoin looping by banning after three rejoins in less than (say) 15 seconds
Implement a blacklist. --- DONE
Allow ops to manipulate blacklist --- DONE
organise black and whitelists to persist to database.
come up with a way for ops (and other?) to look at the banlist (in msg) --- DONE
(maybe) do some kind of flood protection.
perhaps allow blacklist items to be regexps?  Or maybe maintain a seperate
        regexps list...
make white/blacklists case insensitive
accept commands (from ops) in msg rather than in channel