Added comment about calculate_timebase.
Merge branch 'master' of https://github.com/FlightDataServices/FlightDataAnalyzer
Added Track and Track True Continuous for calculating Runway Deviation
Added Airspeed At 8000 Ft KPV
Added AltitudeAtFirstFlapExtensionAfterLiftoff KPV
Added Altitude At Gear Down Selection With Flap Up KPV
Added MachDuringCruiseAvg KPV
Added AltitudeAtLastAPDisengagedDuringApproach KPV
Merge branch 'master' of https://github.com/FlightDataServices/FlightDataAnalyzer