Copter: drift file format fixes

tab replaced with four spaces
Copter: allow override of DRIFT_SPEEDGAIN
Copter: Drift updates control_roll, pitch

control_roll, pitch should always hold desired roll and pitch angles now
that we have the RCIN dataflash message for recording pilot's input
AP_Notify: ExternalLED library
AP_Notify: add Buzzer
Copter: remove CopterLED from main code
Copter: remove LED_ON/OFF defines
Copter: remove PIEZO_PIN definition
AP_Notify: allow external leds to be disabled
Plane: disable external leds
Rover: disable external leds
Copter: enable external leds
AP_Notify: define external led pins for non APM boards

resolves compiler errors
AP_Notify: disable buzzer along with external leds
Copter: reduce SONAR_GAIN to 0.8 (was 2.0)
OptFlow: correct SPI mode and baud rates
Rover: release new beta
Copter: correct optflow logging
Copter: OF_Loiter update control_roll and pitch
RangeFinder: add PulsedLight LRF