Add ICAO code to airport listings

Adding airport code to listing can enhance search for users. For non-fictional registered airports, the uploader can tag the ICAO or IATA code (from navigational database). This way the tagged airport can provide the reference point (coordinates) to display in the map viewer, preventing pints cluttering the map. Multiple listings for a single airports can be consolidated.

This feature can be expanded to the payware store and scenery request marketplace.