Several Bugfixes:

Several Bugfixes:
 * Landing AIAircraft now land properly!!!
 * Fixed problems with takeoff scheduling.
 * Untangled several vertical speed calculation algorithms.
 * No more bent-over-backwards and jump-in-the-air AI aircraft initializations.
 * Fixed intermixed target speed and target altitude during climb phase.
 * Implemented beginnings of a "line up and wait" procedure.
 * Tried to use actual runway elevation for calculating the decent profile.