[conf] pass configured AHRS_x_FREQUENCY on for rotorcrafts as well
[sim] fix symbolic link
[log/replay] this should allow to replay logs including procedures

fix #227
adjusted scaling of ezcurrent sensor
[modules] minor cleanup of ezcurrent sensor
[gps] update doxygen comment
[peripherals] adxl345_spi: set in/out length to fixed 7 again, mixed lenght not working reliably
[rotorcraft] print info if using FAILSAFE_GROUND_DETECT
[peripherals] hmc58xx: fix typo in comment and make explict separate defines for Y,Z data regs for HMC5843/HMC5883
[stm32][spi] select slave after configuring clock/phase, etc of peripheral
Also:
- replace tx_length_case by simpler use_dummy_tx_buf
- minor comment cleanup while here...