Returns a a tuple (options, filename)

        options: The command line options
        filename: String (defaults to None)
        \tThe name of the file that is loaded on start-up

def parse(self):
        """
        Returns a a tuple (options, filename)

        options: The command line options
        filename: String (defaults to None)
        \tThe name of the file that is loaded on start-up

        """

        options, args = self.parser.parse_args()

        # If one dimension is 0 then the grid has no cells
        if min(options.dimensions) < 1:
            print(_("Cell dimension must be > 0."))
            sys.exit()

        # No MDI yet, pyspread can be started several times though
        if len(args) > 1:
            print(_("Only one file may be opened at a time."))
            sys.exit()

        filename = None
        if len(args) == 1:
            # A filename is provided and hence opened
            filename = args[0]
        else:
            filename = None

        return options, filename