Some changes to the API for notifications.
* Don't go through be_roster to send a notification, but use Notification->Send() instead.
* Rename App to Group to make the purpose clearer
And some changes to the notification code itself:
* Use the Notification class as the way to convey informations about a notification. Allows easier extension of this class
* Code cleanup
* Use of the layout kit for the notify window
Unfortunately, the latter part clashes quite a bit with the changes I already did to the notification window, so it's now quite broken. Working on that next, but I wanted to separate that work from the patch ...
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@43114 a95241bf-73f2-0310-859d-f6bbb57e9c96