UFOextender_Gun_Melee rule: lower TU and Power

BattlescapeState: console Stun value as negative.
ExplosionBState: tidy.
ProjectileFlyBState: fix melee attacks w/ loaded ammo.
	tidy & put some additional checks in
TileEngine: remove melee param from voxelCheck()
	- done in hit()
RuleItem: format
BattleUnit: round getAccuracyModifier()