New booking

• Flights should be sorted as follows:
  • GVA pickup (ie Flight Arrivals): By scheduled flight arrival time
  • GVA drop-offs (ie Flight Departures).  By scheduled flight departure time 
    • Note, by "scheduled" I mean the gvach if it exists and the plain scheduled one if not
• Departure times from trips to/from an airport not computed yet.  Should reference the flight arrival or departure times with the formulas agreed.