[conf] add krooz_quad example conf
[conf] replace stabilization euler by int_euler in examples
[airframe] add new airframe for Quark plane
[dox] nicer doxygen formatting for pprz_transport
[dfu] Improved progress bar during programming
[boards] krooz_sd: fix I2C1_GPIO_SDA pin
[i2c] fix i2c3 compilation
[modules] add max7456 osd module
[boards] krooz: baro_board.c corrected
[mcu] Added i2c3 initializationto mcu.c

closes #489
[ardrone2_raw] Battery readout for ARDrone2 RAW version. Formula to convert from 10bit ADC value to battery voltage can be improved
[boards] ardone2: correct voltage scale, thx Eric
[peripherals] updates to l3g4200 gyro from Eduardo
[imu] new GL1 driver from Eduardo

IMU from Goodluckbuy with L3G4200, ADXL345 and HMC5883.
[dox] fix filename in doxygen header
[rotorcraft] only reset psi and integrators if previous mode was not attitude
[imu] aspirin_2_spi: default AHRS_PROPAGATE_FREQUENCY is 512

With DLPF_256HZ (value zero) the internal sampling rate is 8kHz and with a sample rate divider of 1
the output freq was actually 4kHz and not 500Hz. Since the data is polled from the mpu at PERIODIC_FREQUENCY
the AHRS_PROPAGATE_FREQUENCY (defaulting to PERIODIC_FREQUENCY) is also 512Hz for a default rotorcraft config.

Set the output freq to 2kHz now, AHRS_PROPAGATE_FREQUENCY stays at PERIODIC_FREQUENCY=512Hz so doesn't have to be
defined in the airframe file.

Also added defaults for PERIODIC_FREQUENCY of 60 and 120Hz:
- DLPF_42HZ
- output rate of 100Hz
In these cases add <define name="AHRS_PROPAGATE_FREQUENCY" value="100"/>
20s timeout and max 2 retries when trying to update_google_version
[lpc21][uart] fix some unused arg warnings
[modules] silence some warnings in imu_chimu