Throttle trim must be center throttle

Since parameter system will pop message based on meta data

Refactored PX4 radio config to work with both PX4 and APM

- MultiVehicleManager is a Qml friendly replacement for UASManager
- Vehicle is a replacement for both UAS and AutoPilotPlugin

Also:
- Prompts to reset trims to zero prior to calibrate
- Turned of radio check for now since it prevents spectrum bind

QGCUASParamManager and friends are replaced by FactSystem

This way live rc update is correct after a calibrate

- All resources are either under src or under resources dirs
- Removed files top level directory
- Move flightgear files to top level dir