Return local file path from url QML type

As a developer I'd like to have an equivalent of QUrl's toLocalFile() function for QML's url type returning the path of this URL formatted as a local file path, so I can for example display it in the GUI more easily and without manual platform-specific reformatting.

For further reference, see http://stackoverflow.com/questions/38610346/local-file-representation-of-qmls-url-type/38619149