Disable voice's waveforms when it's silent

[Windfisch]

After a voice has finished releasing, turn off its waveforms to avoid it bleeding through due to the leaky VCA

[Sequence7]

I seen you mention this in the code, but also setting the frequency to 0 should stop the sids bleeding their last played frequency as background noise. Also probably tricky to implement (would have to know exactly when notes are playing) the waveforms and gate are atleast in the same register of the sid (thats how it is done in assembly atleast) but the frequency would be a different call.