monkey patch to make vRecur generate an apple iCal comaptible rrule string

vrecur-fix.py

class vRecur(icalendar.vRecur):
    """Fix vRecur so the frequency comes first"""
    def ical(self):
        # SequenceTypes
        result = ['FREQ=%s' % self.types['FREQ'](self['FREQ']).ical()]
        for key, vals in self.items():
            if key == 'FREQ':
                continue
            typ = self.types[key]
            if not type(vals) in icalendar.prop.SequenceTypes:
                vals = [vals]
            vals = ','.join([typ(val).ical() for val in vals])
            result.append('%s=%s' % (key, vals))
        return ';'.join(result)
icalendar.cal.types_factory['recur'] = vRecur