Revision 9234

- Extbans have been implemented. Main implementation done by Adam for p4.
  Currently supported extbans:

  Matching:

   $a:<account>   Matches users logged into a matching account.
   $c:<channel>   Matches users that are on the given channel. An additional
                  prefix of either @, %, or + can be specified to test for
                  certain channel privileges.
   $o:<class>     Matches IRC operators that have joined a class
                  matching the mask.
   $r:<realname>  Matches users with a matching realname.
   $s:<server>    Matches users that are connected to a server matching the mask.
   $u:<modes>     Matches users having the specified user modes set or not set.
   $z:<certfp>    Matches users having the given TLS certificate fingerprint.

  Acting:

   $j:<banmask>   Prevents matching users from joining the channel.
   $m:<banmask>   Blocks messages from matching users. Users with voice
                  or above are not affected.