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

======Description:======
This hook is triggered whenever the client joins a channel, or whenever
it observes another client joining a common channel.

======Parameters:======
|$0    |nickname of person joining channel |
|$1    |channel joined |
|$2    |address of person joining channel (same as $[[userhost function|userhost]]()) |
|$3    |person joining's channel status (on avalon 2.9 servers), could be either (+o) or (+v) |

======Examples:======
To distinguish between the client and other users joining the channel:
   on ^join "*" {
      if ( [$0] == N ) {
         xecho -b You have joined channel $1
      } {
         xecho -b $0 \($2\) has joined channel $1
      }
   }