FlightGear - Flight Simulator FGAddon

MiG-15 3.4.1: Convert most instruments to JSBSim

according to https://www.avsim.su/f/dokumentaciya-obshego-znacheniya-16/samolet-uti-mig-15-instrukciya-po-tekhnicheskoy-ekspluatacii-i-obsluzhivaniyu-kniga-2-26680.html

AGI-I and DGMK-3 drift from abrupt maneuvers not yet implemented (but
they are supposed to self-correct over time anyway).

Very large patch by Michael Danilov: thanks!

Immat: correction for dependency on AirCrane

Cessna L-19: correct dependency on Ryan PT22

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