Chord types

[zmoon]

• Chord or such for the arbitrary explicit chords, a set of notes grouped together to be played simultaneously (e.g. [CEGc])
• NamedChord or such for chords represented by chord symbols, e.g. "Am7", used to annotate suggested accompaniment
  • a step towards ultimate goal of automatic chord suggestions
  • an alternate chord can be added in parens directly after ("G(Em)"; maybe more with comma sep...)