Battle of Britain remake of PSS game CodeSVN

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.

Minor changes.

Added probability to pilotsDead method.
Changed pace of refreshing gamescreen.

Better loading of image files.

Experience is not added instantly now. It is stored as "gained experience" which will be added at the end of the day. So results of pilots' learning in combat are not in effect until the next day. This will prevent fluctuations of experience during the day (eventually lowered at the end of the day by recruits coming to squadrons as replacements) which would be unrealistic.
Added new conditions to painting squadrons on the map: squadrons with status = 7 (mission completed) are painted. German squadrons which are not spotted by radar or observers on ground - are not painted.