Fix for polyphony regression, additional speed up

• Fix polyphonic mode regression.
• Reduce cpu when outputs aren't connected.

UPDATE: still not perfect, or even usable now. A game breaking bug has slept into the recent releases.#13

Use https://github.com/Jon-Biz/VCV-plugins/releases/tag/2.1.1 until these are resolved.

What's Changed

• Speed up process by @Jon-Biz in #12

Full Changelog: 2.1.2...2.1.3