Battle of Britain remake of PSS game CodeSVN

Added map icons of airfields (damaged, cratered runway, when in fog, when in heavy rain) and of radar stations (damaged, non operational)

Cosmetic changes.

Landing and takeoff delays: probably working now. Can't be sure as it's a bit hard to test ;-)

Changed: doesn't allow to land on airfield with cratered runway as runways are repaired only at the end of the day.
Allows to choose airfield for landing when it's covered in fog or runway is damaged but gives a warning (info added on landing button in menu).

Added delay while taking off in bad weather or from damaged airfield.

Starting squadrons while airfield is closed - is not allowed now.
Also squadrons' list doesn't refresh if no changes to squadrons has been made (no take offs, no landings, no refueling nor rearming).

Airfield status changes according to weather (operational/closed)

Added updating weather status of airfields so it shows in info and menu windows.

Added changing weather.

Preparing to add weather.