New option AI_SHOOT_UNSEEN (disabled by default): allow AI to shoot at recently seen/heard enemies (targets that nobody from soldier's team sees currently).

CalcBestShot:
- improved hit rate calculation, take into account possible options INCREASE_AIMING_COSTS, FIRST_AIM_READY_COST_DIVISOR
- minor code improvements
New AI function LOS_Raised checks LOS with forced raised gun status, to get max view distance with scope

git-svn-id: https://ja2svn.mooo.com/source/ja2/trunk/GameSource/ja2_v1.13/Build@8889 3b4a5df2-a311-0410-b5c6-a8a6f20db521

GameSettings.h

@@ -1565,6 +1565,7 @@ typedef struct
 	BOOLEAN fAIMovementMode;
 	BOOLEAN fAIPathTweaks;
 	BOOLEAN fAIDecisionInfo;
+	BOOLEAN fAIShootUnseen;
 
 } GAME_EXTERNAL_OPTIONS;