Introduce QWinThumbnailToolBar and QWinThumbnailToolButton

Change-Id: I55d8f2e01c3647b49d117b2e7e8f7757fa843cba
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>