GitLab

* Introduce a proxy class for thread synchronization
* Use signals for appending text to output window

Change-Id: Iecbb010e6b6e9dab27d9862a43dafa450f2bb1f8
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>