Manage Yui's welcome messages.
Binds goodbye messages to the current channel (Replaces welcome DMs).
Changes the contents of the goodbye message to the given string.
Turns off goodbye messages in the server. Also applies to welcome DMs.
Welcome messages will be sent in a DM instead of a server channel (Replaces server welcome messages).
You may add placeholders to the welcome message which will be replaced when the welcome message is posted.
The tag of the user that joined.
The nickname of the user that joined.
The name of the server.
The server's current member count.
Used to manage Yui's goodbye messages.