Notification level

[SilverRainZ]

We have different requirement for message notification in different chat. For example, if we are in gossip channel, we may not concern about every message except which one mention you. If we are in a serious channel, we want to recevie notification for every message (even members' join/leave message?).

It is not hard to implement such a funcion in Srain, but it would be better to have some discussion and draw a good design.