FlightGear - Flight Simulator FGAddon

Merge trunk to release/2020.3

A320 updates:
- Flight controls: add correct fly by wire failure modes
- General nasal improvements and optimizations
- Corrections for the walker: key bindings / view ordering
- Addition of g-force meter for the fighter pilots out there :-)
- Hydraulic and brake system improvements
- Bugfixes for simbrief parser
- Bugfixes for chocks

Short Empire: fix dependency on Spitfire

MiG-15 3.4.0: improve realism of the cockpit, documentation. Various cleanups.

[Michael Danilov]
* Headsight: fix gyro mode being reversed.
* Hotkey for toggling flight stick.
* Instruments: brake emergency gear, flaps manometers are mechanical, and their needles do not shake.
* 3d: remove emit from external model (leave cockpit emit until cockpit lighting is done)
* Gyrocompass: more sensible heading ticks.
* ASP-3: disable hotspots when stowed.
* Disable canopy hotkey when airborne.
* Manual: https://www.governmentattic.org/14docs/MIG-15pilotOpManual_1955.pdf
* Convert Flapscontrol to knob.

[Jüttner Domokos]
* Convert some cockpit controls to knob animations.
* Move starter button to throttle lever, per pilot's operating handbook.
* Nasal/MiG-15bis.nas (bitswap): delete; use <property-toggle> instead in animations.

Initial import of the A300-600 by Pierre Duval et al

Short Empire: fix xml errors. Correct dependency on Sopwith Camel and Boeing 314.

Update property paths

Aircraft/MPCarrier/Systems/MPCarriers.nas: added optional enabling of ai scenarios plus improved attach.

If /sim/mp-carriers/auto-attach is true, we enable the required ai scenerio
when we see a multiplayer carrier (and open a popup to notify the user), and
also attach more eagerly.

Always latch ai carrier to mutiplayer carrier if we are replaying; this appears
to improve handling of replay if multiplayer replay is enabled.

Added some extra info to /ai/models/carrier[]/mp-control/.

an24b: Made fixes, forgot to commit: AP-28 lateral modes basic fix so far (thanks to awen); SPU-7 NAV2 volume problem; minor fixes

CargoTowingAddon:Correct rope length calculation for panel gauges and scenery visual