Provide a work around for a bug in QFileDialog <https://bugs.launchpad.net/openlp/+bug/1209515>
openlp.core.lib.filedialog.
FileDialog
Bases: PyQt5.QtWidgets.QFileDialog
PyQt5.QtWidgets.QFileDialog
Subclass QFileDialog to work round a bug
getOpenFileNames
Reimplement getOpenFileNames to fix the way it returns some file names that url encoded when selecting multiple files