Battle of Britain remake of PSS game CodeSVN

Bombing airfields: added destroying planes on ground by attacking Luftwaffe bombers.
Added mission target X and Y coordinates to starting data of squadrons (data which is read from file).

Trying some code to destroy planes present on airfield that is being bombed.

Minor bug fix and adjustments to bombing sequence.

Planes bombs their targets. Checks if individual bomber hit its target and how much damage is inflicted. Changes statuses of targets based on damage inflicted.
Still needs some testing. Minor bugs present.

Airfield.java: first draft of inflictDamage method

Removed unused variable.

Bombing sequence: adding experience for bombing, expending ammo (bombs).
Created new variable in Squadron.java: pilotsExperienceBombing - experience in performing bombing mission as opposed to experience in air combat (pilotsExperience).

Bombing sequence: added anti air guns defensive fire.

Bombing sequence: added recognizing of target type - needed to calculate bombing value of squadron (various depending on target).
Squadron.java: added method to calculate bombing value of Luftwaffe bomber squadron.

Added bombing register. Works similar to combat register i.e. remembers which Luftwaffe bomber squadrons are over their mission target and checks if more than one squadron is over given target.