Cleaned up hat effect code (#5462)

Converted from self written container to std::vector.
Converted clif code to struct usage.

src/map/unit.cpp

@@ -3401,12 +3401,8 @@ int unit_free(struct block_list *bl, clr_type clrtype)
 			}
 			sd->qi_count = 0;
 
-#if PACKETVER >= 20150513
-			if( sd->hatEffectCount > 0 ){
-				aFree(sd->hatEffectIDs);
-				sd->hatEffectIDs = NULL;
-				sd->hatEffectCount = 0;
-			}
+#if PACKETVER_MAIN_NUM >= 20150507 || PACKETVER_RE_NUM >= 20150429 || defined(PACKETVER_ZERO)
+			sd->hatEffects.clear();
 #endif
 
 			if (sd->achievement_data.achievements)