autotest: removed obsolete navigation parameters for ArduPlane
AP_GPS: fixed initialisation error in uBlox driver

found with valgrind
AP_InertialSensor: ensure parent class is initialised in instance classes
Plane: removed HIL_MODE_ATTITUDE 

we really need full sensors for HIL with the L1 controller. The flight
is also _much_ better with sensors HIL.
Plane: added LEVEL_ROLL_LIMIT parameter

this replaces both TKOFF_HEAD_HOLD and RUDDER_STEER, allowing users to
instead select a roll limit for takeoff and landing
Plane: update author list