Plane: Bug fixes found during initial testing

Cant set throttle to 0, need to send aparm.throttle_min.get() to kill throttle.
Added VFR HUD message to joystick optimized to see throttle, etc..
Removed uneeded CURRENT_WP message from joystick optimized.
Automatic change to FBWA when going into joystick optimized.
Automatically chagne to AUTO when leaving joystick optimized.
Joystick: Fixed bug found during testing