The mooring code used a settimer loop for no reason, and never
repositioned the aircraft, so it was impossible to start on water
since the flightgear launcher does not allow that. For this reason,
this aircraft was almost unusable, despite its obvious qualities. I
have rewritten Systems/mooring.nas to do mooring in three stages and
without a loop:
1. static initialization, notably of the predefined mooring locations.
2. after FDM initialized, select the closest mooring location and teleport there.
(This implies that whatever airport or location you choose in the flightgear
launcher, you will _always_ spawn at the predefined location closest to it!)
3. after the FDM initializes again, place the buoy model and moor to it.
Additionally I have added two more mooring locations, in Corsica and at
Friedrichshafen. These are fictional in the sense they were not part
of the routes flown by Imperial Airways.
Also, renamed Models/Short_Empire-model.xml -> Models/Short_Empire.xml.
