Feature: Midi - make it possible to handle 'SystemRealTime' events synchronously

[HeckHeckHeckHeck]

Sync more precisely to a Midi clock signal.

[willemOH]

@HeckHeckHeckHeck with your digging into midi clock, do you have any thoughts on this issue?

[HeckHeckHeckHeck]

its just a "back of the envelope" design suggestion prototype. Works for me (perfectly actually).
should probably be shaped and polished a bit little after merge.

[TomFrost]

+1 on this -- I've been ripping my hair out why my Seed inexplicably thought my MIDI channel was switching to 9 spontaneously. I just wrote my own fix at master...TomFrost:libDaisy:fix/midi-parser-running-status to detect the RTClock message before the parser resets. I should have looked here first. IMO @HeckHeckHeckHeck 's solution is more elegant, but I'll keep mine here for reference if it's worthwhile to anyone.

[stephenhensley]

This looks like a solid starting point for improvements with realtime handling to me!

I'll be looking at this and the new related (running status fix) PR early next week.
I'll let you know if there's any feedback, but it looks okay at a glance!

Thanks for the contribution!