FlightGear - Flight Simulator FGAddon

* Wait for the previous item to complete before running a binding
* Add a timeout in case an item condition is never satisifed
* Generalize the sequence of checklists that can be called
* Add ground start and in-air start sequences to 1049h
* Adjust some checklist items to work better with autostart
* Initialize some uninitialized properties
* Fix some bugs in the checklists

Patch from Richard Senior.