FlightGear - Flight Simulator FGAddon

New approach for electrical system / circuit-breakers

Circuit-breaker switches now reside in
/controls/electric/circuit-breakers/*

Power sources are in
/systems/electrical/outputs/suppliers/*

Bus power lives in
/systems/electrical/outputs/bus*

* Add Systems/electrical.xml containing filters to simulate
electrical buses
* implement Left and Right Main Bus circuit breakers
* changed panel lights to new property-scheme

Fixed missing numbers for left main bus circuit breakers on cbpanel