Added a Initialize function for systems.

include/Engine/Core/System.h

@@ -15,10 +15,10 @@ public:
         , m_ComponentType(componentType)
     { }
 	
-	virtual void Initialize();
+	virtual void Initialize() { }
     virtual void Update(World* world, ComponentWrapper& component, double dt) = 0;
 
-private:
+protected:
     std::string m_ComponentType;
 	EventBroker* m_EventBroker;
 };