Mono peak meter using Analog in/out & AudioPeak

Untested, will test it personally in next couple of days but sincerely
expect it will work so committing.

Todo: Test properly. Improve comments and possibly link to wiring
example(s).

examples/MonoPeakMeterAnalog/MonoPeakMeterAnalog.ino

@@ -0,0 +1,39 @@
+/* Mono peak meter example using Analog objects. Assumes Teensy 3.1
+
+At a minimum DC decouple audio signals to/from Teensy pins with capacitors in the signal paths both in and out, 10uF is often used.
+Possibly worthwhile to set up virtual ground at 3v3/2 for both, or if changing DAC REF to 1.2V then 1.2V/2 for output side.
+
+This example code is in the public domain
+*/
+
+#include <Audio.h>
+#include <Wire.h>
+#include <SD.h>
+
+const int myInput = AUDIO_INPUT_LINEIN;
+// const int myInput = AUDIO_INPUT_MIC;
+
+AudioInputAnalog        audioInput(A0);         // A0 is pin 14, feel free to change.
+AudioPeak               peak_M;
+AudioOutputAnalog       audioOutput;            // DAC pin.
+
+AudioConnection c1(audioInput,peak_M);
+AudioConnection c2(audioInput,audioOutput);
+
+void setup() {
+  AudioMemory(4);
+  Serial.begin(1);
+}
+
+elapsedMillis fps;
+
+void loop() {
+  if(fps>24) { // for best effect make your terminal/monitor a minimum of 31 chars wide and as high as you can.
+    Serial.println();
+    fps=0;
+    uint8_t monoPeak=peak_M.Dpp()/2184.5321;
+    Serial.print("|");
+    for(uint8_t cnt=0;cnt<monoPeak;cnt++) Serial.print(">");
+    peak_M.begin();
+  }
+}