realtime-voice-conversion based on last year's work

This is based on the work I did in (July - October)ish 2019 to get real
time voice conversion working. I've removed it from the `voder` library
and made it into an isolable program. I'll work on extending the
capabilities.

README.md

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+Voice Converter Sidecar
+=======================
+This project spins up a Rust binary to handle audio input and output, then 
+ships microphone audio over proto/zeromq to a Python sidecar running
+CycleGAN-VC to convert it into target speech.
+
+### CycleGAN
+I've included a pared down copy of CycleGAN for the purposes of model
+evaluation. It handles all of the audio buffering / sidecar integration
+pieces. [The original CycleGAN I used is here](https://github.com/leimao/Voice_Converter_CycleGAN).
+
+#### Note on Training
+It's possible to train and evaluate at the same time using dual GPUs
+(at least my dual 1080Ti setup). To run the sidecar on a particular
+GPU (0-indexded), use:
+
+```
+CUDA_VISIBLE_DEVICES=1 ./sidecar.py
+```
+
+### Proto Compilation (for Python)
+Codegen for Rust is built in. Codegen for Python uses,
+
+```
+protoc --python_out=cycle_gan protos/audio.proto
+```
+
+### Current Results
+Currently there is 4.39 seconds of delay between speaking and generated output
+with the sidecar setup on my desktop computer. This is really great and seems
+promising.
+
+This gets up to 6.0 seconds later. Drift continues to accrue, but it's a slow
+build.