FlightGear - Flight Simulator FGAddon

Initial import of the Cessna 210 family

DR400-Ecoflyer: Add optional ASI in knots, thanks a lot to Peter (peter.vdgoten on the forum) for a detailed reference image

DR400-Ecoflyer: Reorganise effects, replace KI206 and VSI with new instruments from DA40, update TODO, temporarily remove CB tripping logic

PAR: revert to passing an absolute path to 'play-audio-sample'

This works again since today, namely since SG commit 22779ee2c and FG
commit e7594f4687 on 'next' (doing so didn't work between FG commit
8853fded29 dated 2021-07-27, and these commits). Using an absolute path
here has two avantages:

- the add-on will work again with older versions of FlightGear such as
the 2020.3 release (the previous way, added very recently, required
FG commit 60ff405efc from 2022-08-19);

- access using an absolute path is (slightly!) faster than letting
SimGear's ResourceManager iterate over all providers until it finds
the AddonResourceProvider.

ATCChatter: revert to passing an absolute path to 'play-audio-sample'

This works again since today, namely since SG commit 22779ee2c and FG
commit e7594f4687 on 'next' (doing so didn't work between FG commit
8853fded29 dated 2021-07-27, and these commits). Using an absolute path
here has a few avantages:

- the add-on will work again with older versions of FlightGear such as
the 2020.3 release (the previous way, added very recently, required
FG commit 60ff405efc from 2022-08-19);

- in this particular case, this makes the code simpler (because we use
Nasal's directory() function which doesn't know about [addon=...]
resource path prefixes);

- access using an absolute path is (slightly!) faster than letting
SimGear's ResourceManager iterate over all providers until it finds
the AddonResourceProvider.

Aerotow Everywhere: v1.6.0 (for PlayeRom)

Airspeed-Horsa:Fix key bindings to allow for AI tow plane

Aerotow Everywhere:Initial Commit (for PlayeRom)

SpokenGCA: replace settimer() calls with maketimer()

settimer() has been disabled in add-ons since FGData commit
e39ebd79e3505c4a; use maketimer() instead.

ATCChatter: use a single timer object

Instead of creating a new timer object for every sample, create a single
one at module scope and restart() it in nextChatter() with the
appropriate delay.