Update to how bonuses are calculated in chance to hit code to be

consistent across all relevant effects (treating avoidance
and hit chance bonuses equally).
Rule ArcheryHitPenalty will now calc correctly (Was doing basically nothing)
New field npc_types 'Avoidance' (add avoidance bonus to npc)
Rules for setting min / max chance to hit

zone/npc.h

@@ -333,6 +333,8 @@ public:
 
 	int32	GetAccuracyRating() const { return (accuracy_rating); }
 	void	SetAccuracyRating(int32 d) { accuracy_rating = d;}
+	int32	GetAvoidanceRating() const { return (avoidance_rating); }
+	void	SetAvoidanceRating(int32 d) { avoidance_rating = d;}
 	int32 GetRawAC() const { return AC; }
 
 	void	ModifyNPCStat(const char *identifier, const char *newValue);
@@ -441,6 +443,7 @@ protected:
 	uint32	max_dmg;
 	uint32	min_dmg;
 	int32	accuracy_rating;
+	int32	avoidance_rating;
 	int16	attack_count;
 	uint32	npc_mana;
 	float	spellscale;