Copter: remove set_nav_mode
Copter: remove unused flags and variables
Copter: surface_tracking takes current_alt_target param
Copter: get angle_boost direct from pos_control
Copter: integrate surface_tracking to control_althold
Copter: crash check works with flip flight mode
Copter: remove unused defines
Copter: GCS_Mavlink gets gyro direct from imu
Copter: remove unused init from sport mode
Copter: comment fix
Copter: remove unused parameters
Copter: correct circle rate tuning to use circle_nav