message: including MonoSynth in PolySynth types
diff: @@ -7,6 +7,7 @@ import { Instrument, InstrumentOptions } from "./Instrument";
  import { MembraneSynth, MembraneSynthOptions } from "./MembraneSynth";
  import { FMSynth, FMSynthOptions } from "./FMSynth";
  import { AMSynth, AMSynthOptions } from "./AMSynth";
  +import { MonoSynth, MonoSynthOptions } from "./MonoSynth";
  import { MetalSynth, MetalSynthOptions } from "./MetalSynth";
  import { Monophonic } from "./Monophonic";
  import { Synth, SynthOptions } from "./Synth";
  @@ -22,6 +23,7 @@ type VoiceOptions<T> =
  T extends MembraneSynth ? MembraneSynthOptions :
  T extends MetalSynth ? MetalSynthOptions :
  T extends FMSynth ? FMSynthOptions :
  + T extends MonoSynth ? MonoSynthOptions :
  T extends AMSynth ? AMSynthOptions :
  T extends Synth ? SynthOptions :
  never;
  