Fix timers and game overall playability (#146)

Since the commit related to timers (1c4e25cba0), weird behaviours were encounterd in game so it was unplayable : 
-  When attacking a mob it would aggro but not fight back 
- After 1st spell cats you will hang forever not being able to cast another spell 
- Item spells with cast duraction were not casted properly (Earthstone etc..)

src/game/WorldHandlers/World.cpp

@@ -1677,7 +1677,7 @@ void World::Update(uint32 diff)
 
     ///- Update the game time and check for shutdown time
     _UpdateGameTime();
-
+    GameTime::UpdateGameTimers();
     sWorldUpdateTime.UpdateWithDiff(diff);
 
     ///-Update mass mailer tasks if any