Stages: add CV over the fader, as hardware

[pyerbass]

A trick with the hardware turns each segment in VCO, but can't be done in VCV

• set the segment in LFO - green looping mode
• set the fader at the top to have a C1 note
• Send a 1V/oct sequence in Time/level CV in, then the osc tracks up to C7

In the VCV version, the last point doesn't happen. CV doesn't go higher than the fader position