Changed the format for the flight hours from numeric to time
Added a new class to deal with flight hours
Made use of the new class for mananging the flight hours
Reformatted a style definition
Added support for flight hours without minutes
Removed some last uses of the Time class (is now replaced by FlightHours)
Prepared the code to show the difference between two FlightHours objects
Added support to calculate the actual flight time
Fixed a bug where the takeoff time was not set correctly
Added code to show the takeoff time in UTC
Added two methods to access the fliht hour and minute directly
Added code to calculate all required values