Completely wire up old dataengine and further touches

- Old dataengine is fully functional now
  Except the inhibition stuff but I'm not sure if this is worth keeping the way it is
- "More" menu opens on press now and highlights
- Invoking any action closes the notification now
  KNotification explicitly does that for us but e.g. GTK does not
- Add clear button for history
- Restore kbroadcastnotification support
- Allow forgetting seen application (for KCM)
- Let users "create" notifications by calling NotificationServer::add
- When no application name is provided look up the sender's process name as last resort
- Add kdebugsettings categories file