MappedArray pickling in MultiStateDerivedParameterNode now takes  values_mapping and applies it to itself to ensure that the values mapping is  usable when restoring pickle. Test case added to reproduce scenario.
Warning when None is set to the array... risky; tempting to raise exception instead.
Stable approach fix to take last valid flap setting and to fill masked values as true (stable state). Real test case added too for B737 Classics.