TODO for tuner:

 * rework algorithm setup and padding
 * make max/min freq configurable
 * level triggering for on/off
 * display difference (leds) in not so fine granularity
 * see if real-only FFT is considerably faster
 * make sampling freq configurable
 * make nfft configurable

 * rename the app to Desafinado, Atunality or something