FlightGear - Flight Simulator FGAddon

- Make the CRJ900 JSBSim a variant of the 700 again.
- Make (part of) the flight deck visible over multiplayer. Many of the elements remain
invisible; I don't understand why but this is already an improvement over no flightdeck
at all. The bug was the use of a relative property path for /sim/current-view/internal.
- Remove the annoying bright yellow flashing rectangles surrounding the 6 EFIS screens.
The problem was the use of an absolute path for aliased parameters.