Extended Ban Conditionals (EXTBAN)

* EXTBAN :MODE <channel> <+|-><b|q|e|I> $[~]<type>[:<data>]
* EXTBAN :
* EXTBAN :Extended bans (ban conditionals) allow different checks than the usual
* EXTBAN :nick!user@host or nick!user@ip match to determine whether someone should
* EXTBAN :be banned, quieted, exempted or invited.
* EXTBAN :
* EXTBAN :Extended bans are of the form $[~]<type>[:<data>]. The <type> is one
* EXTBAN :character (case insensitive) and determines the type of match. Most types
* EXTBAN :allow or require an extra field <data>. If the tilde (~) is present, the
* EXTBAN :result of the comparison will be negated, unless the ban is invalid in which
* EXTBAN :case it will never match. Invalid bans are ones where <data> is missing but
* EXTBAN :required or where <data> is otherwise invalid as noted below.
* EXTBAN :
* EXTBAN :Unless noted below, all types can be used with +b, +q, +e and +I.
* EXTBAN :
* EXTBAN : extb Type  - DESCRIPTION
* EXTBAN :------------------------------------------------------------------------
* EXTBAN :     $a     - Matches all logged in users
* EXTBAN :  $a:<mask> - Matches users logged in with a username matching the mask
* EXTBAN :              (* and ? wildcards)
* EXTBAN :  $c:<chan> - Matches users who are on the given channel; this is only
* EXTBAN :              valid if the channel exists and is not +s or +p. (The ops
* EXTBAN :              of the channel the ban is on cannot necessarily see whether
* EXTBAN :              the user is in the target channel, so it should not
* EXTBAN :              influence whether they can join either.)
* EXTBAN :     $o     - Matches opers (most useful with +I)
* EXTBAN :  $r:<mask> - Matches users with a realname (gecos) matching the mask
* EXTBAN :              (* and ? wildcards); this can only be used with +b and +q
* EXTBAN :  $s:<mask> - matches users connected to a server matching the mask
* EXTBAN :              (* and ? wildcards); this can only be used with +b and +q
* EXTBAN :  $j:<chan> - matches users who are or are not banned from a specified
* EXTBAN :              channel
* EXTBAN :  $x:<mask> - Bans all users with matching nick!user@host#gecos
* EXTBAN :     $z     - Matches all SSL users

* Extended Bans
* ----------
*
* Extbans are split into two types; matching extbans, which match on
* users in additional ways, and acting extbans, which restrict users
* in different ways to a standard ban.
*
* To use an extban, simply set +b <ban> or +e <ban> with it as the ban,
* instead of a normal nick!user@host mask, to ban or exempt matching
* users. Ban exceptions on acting extbans exempt that user from matching
* an extban of that type, and from any channel mode corresponding to the
* restriction. Matching extbans may also be used for invite exceptions by
* setting +I <extban>.
*
* Matching extbans:
*
*  j:<channel>   Matches anyone in the given channel. Does not support
*                wildcards (requires channelban module).
*  r:<realname>  Matches users with a matching realname (requires gecosban
*                module).
*  s:<server>    Matches users on a matching server (requires serverban
*                module).
*  z:<certfp>    Matches users having the given SSL certificate
*                fingerprint (requires sslmodes module).
*  O:<opertype>  Matches IRCops of a matching type, mostly useful as an
*                an invite exception (requires operchans module).
*  R:<account>   Matches users logged into a matching account (requires
*                services account module).
* Acting extbans:
*
*  c:<banmask>   Blocks any messages that contain color codes from
*                matching users (requires blockcolor module).
*  m:<banmask>   Blocks messages from matching users (requires muteban
*                module). Users with +v or above are not affected.
*  p:<banmask>   Blocks part messages from matching users (requires
*                nopartmsg module).
*  A:<banmask>   Blocks invites by matching users even when +A is set
*                (requires allowinvite module).
*  B:<banmask>   Blocks all capital or nearly all capital messages from
*                matching users (requires blockcaps module).
*  C:<banmask>   Blocks CTCPs from matching users (requires noctcp
*                module).
*  M:<account>   Blocks messages from users logged into a matching
*                account (requires services account module).
*  N:<banmask>   Blocks nick changes from matching users (requires
*                nonicks module).
*  Q:<banmask>   Blocks kicks by matching users (requires nokicks
*                module).
*  S:<banmask>   Strips color/bold/underline from messages from matching
*                users (requires stripcolor module).
*  T:<banmask>   Blocks notices from matching users (requires nonotice
*                module).
*  U:<banmask>   Blocks unregistered users matching the given banmask.
*                (requires services account).
*
* A ban given to an Acting extban may either be a nick!user@host mask
* (unless stated otherwise, for example M: taking an account name),
* matched against users as for a normal ban, or a Matching extban.
* There is an additional special type of extended ban, a redirect ban:
*
*  Redirect      n!u@h#channel will redirect the banned user to #channel
*                when they try to join (requires banredirect module).
*  -