QNX: Override QPlatformScreen::topLevelAt

Implemented QQnxScreen::topLevelAt method, as base implementation
returned wrong results. This fixes "tst_qwidget widgetAt" for instance.
Removed related method, that is not used at all.

Change-Id: I25c4f474cb0d661e5e5cdcdd0ab13d670fd4dc37
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>
Fix some tst_qwidget test cases

Fixed qwidget test cases for platforms that show windows full screen by
default and that don't support WindowMasks. Incorporated QNX/BlackBerry
peculiarities.

Change-Id: I349ecab5cef35c7d9751aa547465f685d620164a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
OS X: when opening a URL via QFileOpenEvent, pass as QUrl

Opening a file from Finder and opening a URL from the browser are two
different operations, and the URL might not be a local file.

Task-number: QTBUG-39972
Change-Id: I467dfef7efe8eb88c922410db16137e135bc8133
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>