AP_NavEKF: added PositionReset public function to fix pre-arm loss of solution
AP_NavEKF: added static mode for pre-arm and bench testing
AP_NavEKF: reduced On Ground yaw gyro bias drift variance scaler
AP_NavEKF: added PositionReset public function to fix pre-arm loss of solution
AP_NavEKF: Misc tuning adjustments for Plane testing
AP_NavEKF: removed error in constructor comments
AP_NavEKF: fixed bug in variance constraint code
AP_NavEKF: Amended tuning parameter list, and changed from variance to noise definitions
AP_NavEKF: Modifed Vel Pos fusion to fuse height data whenever baro reading has changed
Revert "AP_NavEKF: Modifed Vel Pos fusion to fuse height data whenever baro reading has changed"

This reverts commit d1e1be192a0e7ab0771edc9f2c03547da25697cf.
AP_NavEKF: added position observations to static mode
AP_NavEKF: second attempt at higher rate baro fusion
AP_NavEKF: fixed bug in flag reset for hgt fusion
AP_NavEKF: comment and parameter tweaks for ground testing