clarity:
nav_radial => nav_target_radial (same as selected, except for a LOC)
nav_heading => nav_reciprocal_radial
nav_magvar => nav_twist (it's not always the same as magvar)
nav_heading_needle_deflection => nav_cdi_deflection
nav_gs_needle_deflection => nav_gs_deflection
Added nav_radial back in, but now it shows the current radial from the
VOR, as one would expect. This value also appears in the
/radios/nav[*]/radials/actual-deg property.
hemisphere the distance is positive, if you are in the departure hemisphere
the distance is negature. (Possible use for graphing approach distance
vs. glide slope or cdi.)
