FlightGear - Flight Simulator FGAddon

J3Cub: Refactor, optimize payload logic.

Provide a simple addon skeleton

Add spoken ATC addon

Adopt ATC chatter to new addon api (--addon=/foo/bar switch)

Saab 37 Viggen version 4.105:
Radar: Fixed that radar warning reciever would not check if the aircraft is behind terrain.
Sim: {Pinto} Fixed callsigns with more than 7 chars could not get damaged.
Sound: Fixed missing fire sound from rb71.
Radar: Fixed that GPS selection would return string as flare node.
Sim: Added chaff functionality.
Sim: Fixed regression that missiles would use targets roll for its pitch.
Radar: Fixed RCS calculation would use pitch for roll.
Sim: Fixed heat seeking missiles lock on rear aspect only was flawed, now uses vector math instead of trigonometry.
Sim: Fixed parse error in damage code.
TI: Increased threat circle for SAMs/Frigates.
GUI: Splash screens for 2017.2.1 added.
GUI: Added interior previews.
Sim: Small adjustment to missile APN.
Sim: Fixed that low framerate would make missiles be inaccurate.
Radar: Moved rcs loopup mechanism to rcs.nas
Sim: Fixed regression in heatseekers locking on to sun.

Grrrr files that were not sent on SVN last time :(

Diamond-Da42: do not pollute remote aircraft property trees over multiplayer

* Use relative property names in all model animations. This fixes a bug whereby
a remote DA-42 breaks the keyboard shortcut :Df (for fuel and weight dialog)
in the local aircraft, as well as prevents said dialog from showing gross
weight, if the local aircraft uses yasim (the remote DA-42 would create extra
nodes /sim/weight[4..5] in the property tree local aircraft, among many others).

Diamond-Da42: micro-bug fix.

* Models/da42.xml: when loading a remote DA-42, create its property node
controls/lighting/landing-lights if it does not exist, so we can then alias it
to the multiplayer property (int[10]) it sends for the landing light.

Cirrus-SR22: assorted minor bug fixes.

* sr22-set.xml: add tags.
* Models/Interior/Panel/Instruments/asi/asi.xml: display airspeed correctly under 120 knots.
* sr22-yasim.xml: the nose wheel is castering, not steerable.
* Systems/sr22-keyboard.xml, Systems/help.xml: use Shift+L for landing light, so that L
locks/unlocks the castering nose wheel, which is the default binding. Document.
* Systems/views.xml: add type="double" to default-field-of-view-deg so that model view works.

Update for FG 2017.x.x