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

======Description:======
This hook is triggered whenever the client receives a reply from the
server from a [[SILENCE]] command.

======Parameters:======
|$0 |a '+' if a pattern was added, '-' if one was removed|
|$1 |the pattern silenced (or unsilenced)|