======Synopsis:======
[[on]] [<mode>]public_msg [<serial#>] [-|^]<match> { <action> }

======Description:======
This hook is triggered whenever the client receives a public message in
a channel from someone not actually in the channel.

======Parameters:======
|$0     |nickname sending message   |
|$1     |channel sent to            |
|$2-    |text of message            |

======Examples:======
To customize how these messages are displayed:
   on ^public_msg "*" {
      if ( [$1] == C ) {
         xecho -b \($0\) $2-
      } {
         xecho -b \($0:$1\) $2-
      }
   }