Other unrelated changes are:
a) fixed typo in 'esitmate_velocity' to 'estimate_velocity'.
b) moved init_compass from system.pde to sensors.pde which seemed consistent with other sensors.
* Major change: Log.pde Log_Write_Control_Tuning has changed significantly
* MS5611 has no concept of RawPres and _offset_press
* Log the get_pressure() instead. (If we don't trust the barometer, what's the point?)
Changed timing to be more accurate in main loop. Still need to switch to micros(). Left that for Tridge. This gets rid of six floating point calcs *250. Nice!