diffeditor: Fix qbs build

Change-Id: Ia657fbe20f51657295bfe657a88dab58c668c3f1
Reviewed-by: Jarek Kobus <jaroslaw.kobus@digia.com>
Remove unused code

Change-Id: Icc4bb2648fc4e18e95216012ce08365940a80937
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>