Update CGameEntitySystem (#159)

entity2/entitysystem.cpp

@@ -37,4 +37,17 @@ CBaseEntity* CEntitySystem::GetBaseEntity(const CEntityHandle& hEnt)
 		return nullptr;
 
 	return dynamic_cast<CBaseEntity*>(pIdentity->m_pInstance);
-}
+}
+
+void CGameEntitySystem::AddListenerEntity(IEntityListener* pListener)
+{
+	if (m_entityListeners.Find(pListener) == -1)
+	{
+		m_entityListeners.AddToTail(pListener);
+	}
+}
+
+void CGameEntitySystem::RemoveListenerEntity(IEntityListener* pListener)
+{
+	m_entityListeners.FindAndRemove(pListener);
+}