This enables the specific use case of checking whether a note's release
phase has ended, but is also potentially useful to implement a sort of
"voice stealing" algorithm in Python code, which can take account of
the note's envelope state as well as other factors specific to the
program.
A note can be placed in the center (panning=0) or moved to just the left
(panning=1) or right (panning=-1) channels. Fractional panning values
place it partially in both channels.
.. and account releasing notes at their sustain level until they're
done.
this ameliorates the effect where multiple releasing notes
don't seem to actually be releasing, but stay at a constant volume.
This class allows much more expressive sound synthesis:
* tremolo & vibrato
* arbitrary frequency
* different evelope & waveform per note
* all properties dynamically settable from Python code
This works for me (tested playing midi to raw files on host computer, as
well as a variant of the nunchuk instrument on pygamer)
it has to re-factor how/when MIDI reading occurs, because reasons.
endorse new test results
.. and allow `-1` to specify a note with no sustain (plucked)
In contrast to MidiTrack, this can be controlled from Python code,
turning notes on/off as desired.
Not tested on real HW yet, just the acceptance test based on checking
which notes it thinks are held internally.
