Convert FGNavRecord to inherit FGPositioned. This is much more self-contained than the FGRunway change, since FGNavRecord already had good encapsulation of its state. However, it's a large diff due to moving around two nasty pieces of code - the 'align navaid with extended runway centerline' logic and the 'penalise transmitters at the opposite runway end' logic.
In general things are more readable because I've replaced the Navaid type enum, and the use of Robin's integer type codes, with switches on the FGPositioned::Type code - no more trying to recall that '6' is an outer marker in Robin's data. The creation code path is also pushed down from navdb into navrecord itself.
Attached patch + new file make FGNavRecord have a .cxx file, and a constructor w
hich allows all the parameters to be supplied. Along the way I also cleaned up t
he navrecord.hxx header, lots more header pollution has been killed.
Some long methods are no longer inline, but were all suspiciously long to meet c
ompiler inlining criteria (I'm not clear if the 'inline' keyword is advisory or
mandatory in this situation) - I don't expect this to affect performance in any
way whatsoever.
The constructor addition is to support some hacking I'm doing improving the star
tup performance of the navDB by lazily loading the data, and caching it in a mor
e efficient format than text. I'm submitting this change (and probably some othe
r small tweaks in the future) since they are worthwhile as cleanups regardless o
f how my current experiments work out.
