Virtual Serial Port Driver

What's new in this version:

Launcher:
- Aircraft can now be marked as Favourites, and filtered, making it easier to see find your favourite aircraft out of the hundreds available
- The launcher now supports aircraft carriers, including selecting a carrier and setting a start position

Graphics:
- The Compositor renderer is included as part of this release, but not enabled. It provides a fully XML-configurable multi-pass rendering pipeline that is compatible with ALS and includes clustered shading.
- A new Tower AGL view has been added. This is similar to Tower View, except that it keeps both the aircraft and the ground immediately below the aircraft in view, zooming and panning smoothly as the aircraft moves. Good for viewing landings.
- Use of non-directional point sprites as a fallback for drivers that do not support triangles of point sprites is now supported by setting /rendering/triangle-directional-lights=false.
- Regional textures for Asia, Iceland, Jan Mayen island
- Active volcanoes - Katla, Eyjafjallajokull, Surtsey
- Instanced-based random and OpenStreetMap buildings, improving performance and graphical quality significantly
- Improvements to the Wingflex Shader

JSBSim:
- [Backward compatibility breakage] Gyros are now measuring rotation rates instead of rotational accelerations. Gyros that measure rotational accelerations do not exist in the real world.
- Output properties of flight control elements are no longer tied. This saves a lot of spurious warning messages and allows direct references of the same properties among several flight controls.
- Water vapor in the atmosphere is now managed through its mass fraction rather than its partial pressure. The former being the physical quantity that is conserved when pressure and temperature vary.
- Check that there are at least 3 contacts before trying to trim on ground
- ECEF to ECI frame conversion has been moved from FGLocation to FGPropagate and FGInitialConditions since not all FGLocation need to manage that
- Gravity computations have been moved to FGInertial because it is where all the constants to compute gravity are stored. This reduces the amount of data transmitted between FGInertial and FGAccelerations.
- Added optional transmission of the simulation time for FG UDP interface
- Code cleanup and use more C++11 idioms (override, constexpr, range-based for loop, etc.)
- The existence of the property that is used for table independent vars is now checked during execution rather than when the XML definition is parsed. This relaxes the order in which filters, table and more generally flight controls need to be declared in the XML definition files.

YASim:
- Support for transonic flow effects
- Control initial gear state directly by setting /fdm/yasim/respect-external-gear-state=true, rather then YASim settings this depending on whether the aircraft is in the air or on the ground.
- Electric engines are now supported

Carriers:
- Two new standard state overlays are supported in the launcher: carrier-takeoff and carrier-approach
- A new --carrier-position command-line argument has been added. This can be used to select the aircraft start position on an aircraft carrier. Either a catapult (e.g. cat-1), a parking position (e.g. park-1), on final approach on the FLOLS (flols) or abeam the carrier (abeam).

AI:
- New AI models for the CRJ900, SR-71, Saab 340
- Updated AI models for the A-4, KA6-D, ERJ-195, CRJ-700, CRJ-200
- Updated AI traffic for Aeormar Mexico, AirDolomiti, Air Tahiti, American Eagle, China Southern, Delta Connection, Horizon Air, IcelandAir, JetBlue, LoganAir, LOT, Lufthansa, Lufthansa CityLine, MNG (Cargo), SkyUp, United Parcel Service, Ural Airlines, Uzbekistan Airways, Westjet Regional.
- Updated AI liveries for Aeormar Mexico, Airbus, Air Canada, Air Europa, Air Tahiti, American Airlines, American Eagle, Alaska, Belavia, China Southern, Gulf Air, Hop!, Icelandair, JetBlue, LoganAir, LOT, Rusline, SkyUp, South African Express, United Express, Ural Airlines, Uzbekistan Airways, Virgin Australia, Westjet,
- Space Shuttle TAEM and approach at KEDW scenario
- Accurate Britten-Norman Islander performance data, from an Islander pilot

Multiplayer:
- FGComm now supports both COM1 and COM2, as well as volume settings
- The views defined by the user's aircraft (Pilot view, Helicopter view, Tower view etc) can now be used with multiplayer aircraft. Viewing a particular multiplayer aircraft is done by clicking in the Pilot List dialogue's "view' column (see the "Multiplayer/Pilot List" menu).
- Connection to VATSIM via swift is now available via the GUI
- disable-hold-short option which allows the user to force a start on the runway when multiplayer is enabled. This option should be used with caution - it can give other pilots and ATC a nasty fright to find an aircraft materialize on the runway!
- MPCarrier can now be detected by the GUI even if not available on startup. To enable this feature set /sim/mp-carriers/auto-attach=true

Nasal Scripting:
- Garbage collection improvements to reduce frame stuttering
- Re-loadable nasal modules
- Canvas EFIS framework

Canvas:
- Three new methods in Canvas Image to set colors of pixels in the image

Aircraft:
- Boeing 777
- Douglas A-26-Invader
- Airbus A320
- Antonov AN-24
- Diamond DA40 NG G1000
- Robin DR400 Ecoflyer
- General Dynamics F-16
- Piper J3 Cub
- Saab JA37 Viggen
- Piper PA 28 Cherokee
- Bombardier Q400
- Ryan Navion
- Space Shuttle
- Cirrus SR22
- Yak 52
- Miscellaneous
- Increased turbulence will be encountered near active volcanoes
- Configurable METAR URL
- METAR strings are decoded and displayed in a human-readable form in the weather dialog
- Polish translations of the UI are now available
- Improved Chinese translations for the launcher
- Improve glider vario instrument