Refactored singletons to enable proper deconstruction during shutdown

src/server/game/Scripting/ScriptMgr.h

@@ -881,8 +881,8 @@ class ScriptMgr
     public: /* Initialization */
         static ScriptMgr* instance()
         {
-            static ScriptMgr* instance = new ScriptMgr();
-            return instance;
+            static ScriptMgr instance;
+            return &instance;
         }
 
         void Initialize();