[Azoth Xoox] No point in photo hash for room participants.
[Azoth Xoox] Don't check if avatar is equal to current on start.

Most likely it isn't (if it isn't null), so avoid this tremendous slowdown.
[Azoth Xoox] Async avatars loading.
[Kinotify] Support having QImages in NotificationPixmap.
[Azoth] Avoid double-serializing notification pixmaps.
[Azoth] Emit QImages in NotificationPixmap instead of QPixmaps.

Avoids useless conversions.