Split segments fallback_dt is now relative to the end of the data  not the start
copy  to temp file for processing
log a warning when datetime does not increment enough as expected; TODO: Review whether an error should be raised.
fallback_dt fix
Use np.ma.sum() rather than sum() to avoid issues with masked values returning "masked" as the sum result.
Altitude First Stable and Last Unstable split into two to easily segregate the non-landing approaches (go around) and those which were landed (full stop landing) for statistical analysis.

New KPV for Last Unstable State (split into two as above).

PercentApproachStable now accounts split as above (before go around and last landing) in addition to the two altitude bands.

Test cases added and updated to reflect new requirements.
Stable Approach modified to use Eng (*) N1 Min [For 5 Sec] and Airspeed Relative [For 3 Sec]  in order to provide more tolorence.
Should Vapp be recorded, a tighter constraint is applied.
Stable Approach limit changes as below and all thresholds are now inclusive of the threshold being tested (< now <= etc).
- Glideslope ignored below 200 feet (was 100) 
- Localizer ignored below 200 feet (was 100)
- Vertical Speed descent now -1000 fpm (was 1300) NOTE: Moving average window likely to increase.
Merge branch 'master' of github.com:FlightDataServices/FlightDataAnalyzer