messageAll(callback, message, arg0, arg1, ...)
Loops through clientGroup, and calls messageClient on every member.
messageAllExcept(client, callback, message, arg0, arg1, ...)
Loops through clientGroup, and calls messageClient on every member except client.
messageClient(client, callback, message, arg0, arg1, ...)
Literally just commandToClient(client, 'serverMessage', callback, message, arg0, arg1, ...)