AP_InertialSensor: Correct out-of-bounds array access that was causing SITL to crash
SITL: simulate dual accel/gyro
AP_NavEKF : Fixes zero compass offsets on initialisation
AP_NavEKF: give a sensible error for no such file on replay
Replay: moved replay tool into Tools/Replay
Replay: added parameter handling

use parameters from log, and allow override
Replay: added accel and gyro mask options
Replay: fixed -g option
AP_NavEKF : Add accel aliasing protection
AP_NavEKF : Add div0 protection to the IMU1_weighting calc
AP_NavEKF : Fix bug that prevents Zacc bias state variance being updated
AP_NavEKF : Use average of dual IMU gyro data when available
AP_NavEKF: don't assume the number of gyros == number of accels
AP_NavEKF: cope with compass going offline while in flight
RC_Channel: Removed duplicate defines from RC_Channel.h
Tools/AntennaTracker: removed duplicate update_tracker from task list
Tools/AntennaTracker: completed intial tracker code

Now works with 2 servo alt-azimuth mounted antenna tracking mount. Tested
on Flymaple, with Eagle Tree antenna tracker.
Tools/AntennaTracker: remove redundant comment
autotest: sim_arduplane.sh works with a range of terminal types
Rover: only send GPS2_RAW when we have a 2nd GPS