Vehicles - Add Auto-Throttle to Planes

[TheCandianVendingMachine]

When merged this pull request will:

• Add a speed-limiter type control to planes

Uses a basic PID Controller to control the throttle of a plane to keep it at some speed. PID was tuned in Simulink, so values work well. Once you have speed limiter on, you don't have to touch the throttle again.

Video of it in action

[PabstMirror]

Close #2818 (I think)

[jonpas]

Why only planes? Most cars today have cruise control / tempomat. I assume the PID tune would be different though, so if you don't want to do that, that's fine. :D

[PabstMirror]

ground vics are getting in-engine cruise in 2.06
https://community.bistudio.com/wiki/setCruiseControl

[jonpas]

Ah right! We have another PR somewhere for that already as well.
EDIT: Just for limit, but an actual use of cruise control for ground vehicles would be cool too.

[TheCandianVendingMachine]

I don't think there is a way to control the throttle in non-plane vehicles, so I'd have to go into the config and setVelocity appropriately and it just turns into a mess

[jonpas]

setCruiseControl has autoThrust.

[dedmen]

Somewhat unrelated to this PR

PID was tuned in Simulink

Engine setCruiseControl has hardcoded PID params that might not be optimal
kp = 0.5
ki = 0.3
kd = 0.2
maybe that can be tuned better.
If you can optimize that and find better values, feel free to contact me and i can transfer them into the engine vehicle PID, but it needs to work with all vehicles from quads to tanks