FlightGear - Flight Simulator FGAddon

Harrier-GR3/Systems/Autopilot.xml: set startup-zeros to false in vertical speed pid controller.

Reduces oscillations when activating vertical speed, but requires support in
fgfs itself.

Harrier-GR3: in 'Harrier' menu, add item to toggle terrain map.

This helps framerate, e.g. from 23 to 28fps.

Disables if property /sim/terrain-map is 0; this property is saved to
aircraft-data so will persist between sessions.

Harrier-GR3/Nasal/autohover.nas: minor diagnostic fix.

Harrier-GR3/Models/Harrier-GR3.xml: use surface-positions, not controls/flight.

This make elevators, ailerons and flaps animate when viewing multiplayer.

Harrier-GR3/Systems/Autopilot.xml: fixed indentation.

Harrier-GR3: Various changes to autohover horizontal.

When we land, don't turn off completely; take control again when we next leave
the ground.

Horizontal target: alt + cursor-keys now moves target position by small
amount. Show target distance in ft, not m.

Harrier-GR3: added auto-hover vspeed land.

Uses autopilot vertical speed control to perform smooth landings.

Alt-l toggles auto behaviour - activate when we intercept landing profile.

Also reduced autopilot vertical-speed Ti to improve behaviour if horizontal
speed changes.

Harrier-GR3: allow reload of auto-hover code.

Changed all code to use new wrappers for setlistener() and maketimer() that
store all registered handlers so that they can be cleaned up when we reload.

PA28: Aerodynamic improvements by Niels Krenz

DR400: minor fix (thanks D-SVEN)