ArduPPM V2.2.66

- Added APM2 (ATmega32U2) support for using TX and RX status leds to indicate PWM and PPM traffic

<RX><OFF> no pwm input detected
<RX><TOGGLE> speed of toggle indicate how many channels are active
<RX><ON> input lost (failsafe)
<TX><OFF> ppm output not started
<TX><FAST TOGGLE> normal PWM->PPM output or PPM passtrough failsafe
<TX><SLOW TOGGLE> PPM passtrough