Android: Output QML import and root paths for qmlimportscanner

When deploying QML applications, the androiddeployqt tool can
use qmlimportscanner to detect the QML dependencies of the
application, but then it needs to know the root of the project
as well as additional QML import paths. We use the already-existing
QML_IMPORT_PATH for the import paths, and default to using the
location of the .pro file for the root path (same as for static
builds in qt.prf).

Change-Id: Ib536272ed1f3f1320ea8ef529655e2ba003bc734
Task-number: QTBUG-34175
Reviewed-by: BogDan Vatra <bogdan@kde.org>
Fix high DPI icons in menu items

The position of high DPI icons is wrong in the Fusion style because
the pixel resolution is not taking into account when centering them.

Task-number: QTBUG-40277
Change-Id: I3593ed461ea57543c3ddfd473105fdc698789132
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Make QOpenGLWidget public

QOpenGLWidget is now public.

In addition Qt::WA_AlwaysStackOnTop is introduced to support the
special case of semi-transparent QOpenGLWidget or QQuickWidget on
top of regular widgets.

hellogl_es2 becomes the qopenglwidget example. This example performs
painting both via QPainter and native GL commands and has the OpenGL
widget combined with other, normal widgets.

The widget stack receives some changes when it comes to renderToTexture
widgets like QQuickWidget and QOpenGLWidget. Calling update() will now
result in a paint event, which is essential for QOpenGLWidget since we
want it to behave like a regular widget. The dirty region handling is
extended specially for such widgets due to performance reasons.
(an OpenGL content update must not result in any backingstore painting,
and is thus handled as a different kind of dirtiness)

[ChangeLog] Added QOpenGLWidget. This widget serves as a replacement for QGLWidget.

Task-number: QTBUG-36899
Task-number: QTBUG-40086
Change-Id: Ibf7f82fea99b39edfffd2fc088e7e0eadbca25cf
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>