preparing serialization of entities

Game/Entity/EntityManager.cpp

@@ -28,7 +28,13 @@ void InitEntityManager(NonNullPtr<World> world)
 
 void ShutdownEntityManager()
 {
-    GetEntityManager().Entities.Destroy();
+    auto& manager = GetEntityManager();
+    for (typed_entity_array& type : manager.by_type)
+    {
+        ArenaRelease(type.arena);
+    }
+
+    manager.Entities.Destroy();
 }
 
 EntityManager& GetEntityManager()
@@ -37,8 +43,6 @@ EntityManager& GetEntityManager()
     return *entityManager;
 }
 
-void Serialize(NonNullPtr<EntityManager> entityManager) {}
-
 entity_template* RegisterEntity(EntityManager& manager, Entity* base, DerivedType entity)
 {
     base->ID      = EntityManager::ID++;
@@ -61,6 +65,11 @@ entity_template* RegisterEntity(EntityManager& manager, Entity* base, DerivedTyp
     return ptr;
 }
 
+void RegisterBaseEntity(EntityManager& manager, Entity&& base)
+{
+    GetEntityManager().Entities.PushBack(std::move(base));
+}
+
 void UpdateEntityManager(EntityManager& manager)
 {
     // Todo : inert by definition dont move, but this is for test