Invert order of messages in notifications (#888)
Invert order of messages in notifications (#888)

Previously the latest message was on top. But that resulted in
weird situations when multi-line messages are part of the notification.

With this change, all new messages are appended to the notification, so
you can read them from top to bottom.
threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web