AP_InertialNav: use references to AHRS and baro
Copter: fixed build for InertialNav change
HAL_AVR: fixed build warning
AP_NavEKF: added healthy() API
AP_AHRS: check for NavEKF health
Copter: removed HIL_MODE_ATTITUDE

this really can't work any more, as AHRS can't support it
Plane: cleanup HIL defines
Rover: cleanup HIL defines
VARTest: cleanup HIL defines
build: make hil equal hilsensors
AP_AHRS: removed unused AP_AHRS_HIL
Rover: enable use of AHRS_NavEKF
Copter: enable use of AHRS_NavEKF
Plane: change for new AHRS API
AP_AHRS: pass baro into AP_AHRS

first step in making AHRS handle altitude
Copter: fixed build for new AHRS API
VARTest: fixed build
DataFlash: only fsync every 10 seconds

prevents too much work in SITL
AP_NavEKF: handle conversion of AHRS to handle altitude

fixed accuracy of position for cm level lat/lng
AP_L1_Control: no need to project position for lag

now handled by AHRS