Direct2D QPA: Disable vsync

We shouldn't block the whole gui thread for vsyncing. This can slow things
down a lot if a lot of drawing happens.

Change-Id: Ie459f9dee2271e7908e2b7f56873393c67f82836
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Direct2D QPA: Optimize Clipping

Use axis aligned clips when possible instead of layer-clipping. This can
be much faster when a lot of clipping operations take place.

Change-Id: I6865d69fc917a7da858033b4c362b307724d9006
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Direct2D QPA: Fix paint engine state handling

Fix the paint handling to support QPaintEngineEx style state updates. This
fixes most of the outstanding issues, as QPainter save and restore were
essentially broken before

Change-Id: I477d8acfd71bba32dfac4c491bc5bbaad1804ec5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Direct2D QPA: Improve software fallback mechanism

Improve the way we fall back to the raster engine by forwarding painting
state. Amongst other things this makes perspective transforms appear
correct.

Change-Id: I729de56ef3112bbc01516fc11c295f33a2aada0d
Reviewed-by: Risto Avila <risto.avila@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>