WT VCO locks mutex too often/too long in the GUI thread

[Xenakios]

and that causes audio pops/noise in the module's output.

The most offending mutex locking is at

https://github.com/VCVRack/Fundamental/blob/5c7a2bfe14b2edf73669ea5d04d65112a192f778/src/Wavetable.hpp#L329

Since that method is run at each GUI update (dozens of times per second) when the module panel is in view, the audio thread will try to enter the mutex quite often while it is locked by the GUI thread, and because of how the audio processing is implemented (early return from process() ), pops/noise is heard in the module audio output.

Perhaps a solution that doesn't involve using a mutex lock for the module's thread safety could be devised?