Manage Yui's goodbye messages.
Binds goodbye messages to the current channel.
Changes the contents of the goodbye message to the given string.
Turns off goodbye messages in the server.
You may add placeholders to the goodbye message which will be replaced when the goodbye message is posted.
The nickname of the user that left.
The name of the server.
The server's current member count.
The amount of time the member was in the server.
Used to manage Yui's welcome messages.