Move wave play/record into separate module.

wave.py

@@ -0,0 +1,18 @@
+import os
+import signal
+import subprocess as sp
+
+from common import Fs
+
+def play(fd):
+    args = ['aplay', fd.name, '-q', '-f', 'S16_LE', '-c', '1', '-r', str(int(Fs))]
+    ret = sp.call(args=args)
+    assert ret == 0
+
+def record(fname):
+    args = ['arecord', fname, '-q', '-f', 'S16_LE', '-c', '1', '-r', str(int(Fs))]
+    p = sp.Popen(args=args)
+    p.stop = lambda: os.kill(p.pid, signal.SIGINT)
+    return p
+
+