pair of lower/upper bound iterators.
Sometimes when iterating the list, like in cs_mode, we can modify the
contents of it, which combined with mlock always agressively trying to
readd modes to it can do bad things.
This allows fully tracking extbans and other modes set by a different
underlying mode, such as InspIRCd's namedmodes
Add two configuration options to cs_ban to configure which mode is set
and whether or not to kick banned users.
Add default "mute" fantasy command to botserv.example.conf
Adam