[mcu_periph] Fix error sending
[tests] Fixed build of PWM tests
[bmp085] Fix calibration reading with errors
[fix] typo in githelper script

close #710
[ardrone] Slow-Down Heading rate
[energy_ctrl] Energy loops not being called. Code commenting.
[airframe] Default Energy Gains Simulator
[agl] use ground_alt from autopilot if no SRTM data available
[rotorcraft] remove unused RC_LOST_MODE from autopilot.c

RC_LOST_MODE is correctly defined and used in main.c
[conf] stm32 upload: fix DFU_SIZE on OSX
[datalink] w5100: rename too generic rx_buf var
[rotorcraft] guidance_h speed ref saturation fix

Bound ref to max accel along reference vector.
If angle can't be computed, simply set both axes to max magnitude instead of zero.

Should (tm) fix #716
[conf] sort conf example and test
[optitrack] Give feedback about following drones and fix gps
[conf] stm32-upload: only verify for dfu-util >= 0.7
Merge pull request #718 from fvantienen/optitrack_fix

[optitrack] Give feedback about following drones and fix gps
[subsystem] possibility to poweron gps and imu via gpio at init

closes #706
[airborne] check ned_initialized_f in stateIsLocalCoordinateValid
[ins] alt_float: properly reset_alt_ref if !USE_BAROMETER
[ins] ins_int: INS_SONAR_MIN_RANGE defaults to 1mm