Setting the Qt::AA_EnableHighDpiScaling attribute makes sure that the
scrollbars are scaled, and that the default zoom level is sensible.

Task-number: QTBUG-54113
Change-Id: I0ae7eb97cb9e2824e7f9b92d77cf2986cac66685
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

...to use the external link specified in
qtbase\doc\global\externalsites\qt-webpages.qdoc

Change-Id: Ieeade45440a5454ec7856230510f3914b1a56800
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

Task-number: QTBUG-51383
Change-Id: I872bdae7267e7dbf2a93a831d435517bcd4bad64
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>
Reviewed-by: Michal Klocek <michal.klocek@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>