also adds AMSL output in ft

SLUGS has maintained their patches out-of-tree for a long while now.
These will eventually get merged back in, but it'll be easier to evaluate them as fresh commits instead of modifications to this old & dead code, so we'll delete this for now.

Impl. Lorenz suggestions wrt one velocityChanged, altitudeChanged, speedChanged signal per reference frame. Impl. CDI on compass disk.