Fix ReloadQuest on Shutdown crash related to encounters

Basically, EntityList::RemoveAllEncounters is called before ReloadQuests
resulting in stale pointers in the lua_encounters map.

We just have to remove the entry from the map.

zone/quest_parser_collection.h

@@ -65,6 +65,7 @@ public:
 	void AddVar(std::string name, std::string val);
 	void Init();
 	void ReloadQuests(bool reset_timers = true);
+	void RemoveEncounter(const std::string name);
 
 	bool HasQuestSub(uint32 npcid, QuestEventID evt);
 	bool PlayerHasQuestSub(QuestEventID evt);