- exclude POIs and some other types from the ident match, to avoid
confusing results
- improve how the search vicinity is computed when inserting a leg,
which is the common case for a route with a destination set. Use
the midpoint of the leg ending at the insert position, as the optimal
search vicinity
- move the waypointFromString code into route.cxx, since it is mostly
independent of a FlightPlan instance
- extend the tests to cover the bug which flagged these issues
Ticket-Id: https://sourceforge.net/p/flightgear/codetickets/2372/
72f1b84837