Gyro compass based on jsbsim instead of FG properties

[vanosten]

Copied from wiki-article (https://github.com/l0k1/MiG-21bis/wiki/Navigation): the gyro compass is implemented using FG's property rules system, which may cause some issues with accuracy if frame rate is very low. this should be ported to use jsbsim instead, however this is low priority for me at this time.

[vanosten]

Later down in "Navigation using internal system" as similar developer note has been added: this system is implemented using FG's property rules system, which may cause some issues with accuracy if frame rate is very low. this should be ported to use jsbsim instead, however this is low priority for me at this time.

Not sure whether it is the same - but it is the same theme.

[l0k1]

Duplicates of #22 and #23, which were closed. If someone wants to rewrite them, I'm okay with it, but I'm not going to be pursuing this until after version 1 at the earliest.

Edit: probably shouldn't have closed those 2, so thanks for reopening this. :)

[l0k1]

I lied. With the implementation of the various gyro's, it seemed like a good time to rewrite these to take full advantage of them.