This effectively means that an RTL kicked off by a failsafe will
immediately switch to LAND mode only if within 2 meters. Previously the
radius was much wider (15m).
Failsafe events changed to errors so they are more obvious.
Errors recorded to dataflash for failure to init compass and optical flow sensor.
Errors recorded for pwm failure.
Resolved a compile error when dataflash logging is disabled.
Switch to LAND flight mode if throttle failsafe triggers and we do not have a GPS.
THR_FAILSAFE renamed to FS_THR_ENABLE.
THR_FS_VALUE renamed to FS_THR_VALUE.
THR_FS_ACTION removed (action is now controlled by setting FS_THR parameter).
resolves momentary throttle drop to zero before failsafe engages
resolves motor cut after 30seconds if flying in stabilize without GPS (now switches to ALT_HOLD with target altitude zero)
disables motors if throttle was zero before failsafe event
Merged CopterLEDS and Piezo functions to eliminate pin conflict on APM2. Created new Parameter bit to turn piezo function on and off from MP. Moved GPS and Aux pin assignments to allow commonality between APM1 and 2. Set LED_Mode parameter default to 9 in order to make CopterLEDS completely backwards compatible with old Motor LEDS and Piezo code. Legacy users should see no difference.
