Motivation

When composing a base sound with chords it is hard to emulate rhythm using only the duration propertie.
It would be nice to have a way to pass a propertie called rhythm to emulate known durations for rock or other styles.

DoD

A sequence of chords may be instantiated as below:

chord_sequence = Chord.build_with_rhythm(
  'A.-1'
  duration: 0.9,
  volume: 0.8,
  times: 1,
  rhythm: :rock
)