match_altitudes reworked

The original version fell over if there was corruption leading to masked
values, following which the fine part would be out of step with the
preceding data. This reworked version computes the matching offsets in
chunks of valid data, thereby solving this problem.
gear travel update and taxi phases reduced

Gear Extending and Retracting phases use red warnings, but sometimes one
of these is not available. Phases reworked to not rely upon all being
available.
Taxi phases pick up the Mobile duration to limit the time on stand, and
hence improve the quality of data monitoring for the taxi phases.
match_array test update
ILS Marker combination for multi-source aircraft
Engine start not reliant on engine 1 data being valid.
Trap for data with no liftoff

Applies to the "AltitudeAtFirstFlapChangeAfterLiftoff" KPV