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.

build.rs

@@ -0,0 +1,11 @@
+extern crate prost_build;
+
+fn main() {
+  //prost_build::compile_protos(&["protos/audio.proto"],
+  //                        &["protos/"]).unwrap();
+  prost_build::Config::new()
+      .out_dir("src/protos/")
+      .compile_protos(&["protos/audio.proto"],
+                      &["protos/"])
+      .unwrap();
+}