MIDI in simulator (#4761)
MIDI in simulator (#4761)

* basic sim support for midi

* tweaks to audio manager

* ignore velocity

* logging

* no offset needed

* handle mute

* adding webmidi typings

* fixing tsconfig

* removed typings

switch-education/pxt,Microsoft/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt,switchinnovations/pxt,playi/pxt,switch-education/pxt,playi/pxt,playi/pxt,Microsoft/pxt,switchinnovations/pxt,switch-education/pxt,playi/pxt,switchinnovations/pxt,Microsoft/pxt,switch-education/pxt,switchinnovations/pxt