Check Chord duration creation

[mscuthbert]

music21 version

8alpha

Problem summary

Check whether the duration code in ChordBase can be simplified:

        super().__init__(**keywords)

        # inherit Duration object from GeneralNote
        # keep it here in case we have no notes
        durationKeyword = None
        if 'duration' in keywords:
            durationKeyword = keywords['duration']

        durationKeyword = self._add_core_or_init(notes, useDuration=durationKeyword)

        if durationKeyword is not None:
            self.duration = durationKeyword
        elif 'type' in keywords or 'quarterLength' in keywords:  # dots dont cut it
            self.duration = Duration(**keywords)

it seems like all this information already is handled in Music21Object

[mscuthbert]

except the self._add_core_or_init line