FlightGear - Flight Simulator FGAddon

* import ZKV500 GPS into Models/Instruments/zkv500
* fix wrong mouse-button on power-button
* add texture (Models/flightdeck.png)
* include into emis-animation

* add maplights on flightdeck
* change some init-values for interior lights in
Nasal/electrical.nas

* overhauled materials in cabin.ac and flightdeck.ac
* fixed some small holes between cabin.ac and flightdeck.ac
* experiments with fake ambient light on flightdeck (would need an
average light amount of all flightdeck lights to work properly)