WesterboerVW921: Fixed airspeed reading

According to the documentation provided by Westerboer, the airspeed is
transmitted as 0.1 m/s. The users of this driver have confirmed though
that this is wrong and 0.1 km/h is actually transmitted.

Flight test and validation performed by Kimmo Hytönen
Geo/FlatGeoPoint: apply naming convention
Route/AStar: add comparison operator to template arguments
Geo/SearchPoint: remove operator<

This comparison operator is not "natural", and may make the code
obscure.  Clients who need this shall call the Sort() method instead.
Geo/SearchPoint: apply naming convention
TracePoint: remove obsolete constructor
TracePoint: make conversion constructor "explicit"

Avoid costly implicit conversions.
TraceComputer: remove unused attribute last_time
TraceComputer: merge two checks
TracePoint: add scratch constructor
TracePoint: construct from MoreData object
Trace: pass TracePoint to push_back()

Simpler API that does not depend on AircraftState.
ScoredTaskPoint: replace state_exited with boolean flag

This is only used in HasExited().  Reduce overhead.
Engine/Aircraft: include cleanup
TraceComputer: use MoreData instead of AircraftState

This is simpler to use, because AircraftState is an unnecessary
intermediate step that adds overhead.
ContestDijsktra: update append_serial in UpdateTraceTail()

Fix bogus calls.
Trace: increment append_serial on all changes

Simplify ContestDijkstra::UpdateTrace() by returning early on
unmodified Trace.
ContestDijkstra: remove bogus check
ContestDijkstra: move code to UpdateTraceFull()
ContestDijkstra: simplify UpdateTrace()

Eliminate the "return" by adding an "else" branch.