QWindow::setWindowFilePath added

QWindow::setWindowFilePath added

QWindow::setWindowFilePath sets the file path of the document
that is currently represented by the window.
The window system might display it in the window's title bar
along with an icon matching the file type.

Task-number: QTBUG-27299
Change-Id: I8f620d1262fc0b4cd16884198b16853b73ce3b1f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>