/* Join a user to a channel. May be a channel that doesnt exist yet.
* @param user The user to join to the channel.
* @param cn The channel name to join to. Does not have to exist.
* @param key The key of the channel, if given
* @param override If true, override all join restrictions such as +bkil
/* Join a user to a channel. May be a channel that doesnt exist yet.
* @param user The user to join to the channel.
* @param cn The channel name to join to. Does not have to exist.
* @param key The key of the channel, if given
* @param override If true, override all join restrictions such as +bkil