common code: Add feature to record received audio and replay it

-W <file.wav> writes a wave file of received audio
-R <file.wav> reads a wave file to feed into decoder

This way you can record a phone and later debug without a phone
and radio equipment.

src/bnetz/main.c

@@ -154,7 +154,7 @@ int main(int argc, char *argv[])
 	}
 
 	/* create transceiver instance */
-	rc = bnetz_create(sounddev, samplerate, kanal, gfs, loopback, (double)lossdetect / 100.0, pilot);
+	rc = bnetz_create(sounddev, samplerate, write_wave, read_wave, kanal, gfs, loopback, (double)lossdetect / 100.0, pilot);
 	if (rc < 0) {
 		fprintf(stderr, "Failed to create \"Sender\" instance. Quitting!\n");
 		goto fail;