add wavy example code

examples/record.rs

@@ -0,0 +1,35 @@
+//! NB: From wavy library
+//!
+//! This example records audio and plays it back in real time as it's being recorded.
+
+extern crate wavy;
+
+use wavy::*;
+
+use std::collections::VecDeque;
+
+fn main() -> Result<(), AudioError> {
+    println!("Opening microphone system");
+    let mut mic = MicrophoneSystem::new(SampleRate::Studio)?;
+
+    println!("Opening speaker system");
+    let mut speaker = SpeakerSystem::new(SampleRate::Studio)?;
+
+    println!("Done");
+
+    let mut buffer = VecDeque::new();
+
+    loop {
+        mic.record(&mut |_index, l, r| {
+            buffer.push_back((l, l));
+        });
+
+        speaker.play(&mut || {
+            if let Some((lsample, rsample)) = buffer.pop_front() {
+                AudioSample::stereo(lsample, rsample)
+            } else {
+                AudioSample::stereo(0, 0)
+            }
+        });
+    }
+}