implement qHash(const QRectF &)

If you declare something like

    QHash<QRectF, MyClass*> m_monitoredAreas;

you will run into the problem that qHash is not defined for QRectF. It seems like something we could provide. My naive implementation is

uint qHash(const QRectF &r) {
    return qHash(r.width() * 1000000000 + r.height() * 1000000 + r.x() * 1000 + r.y());
}

At least it's possible to do this in the application.