HasManyIds does not reflect additions to HasMany relationship

[zeitlerc]

If an entity is added to a HasMany relationship collection, it should be added to the Ids in HasManyIds. That is currently not the case within the same session.

[Model]
public class Person
{
    [HasManyIds("pizzas")]
    public IEnumerable<Guid> PizzaIds { get; set; }
    [HasMany]
    public ICollection<Pizza> Pizzas { get; set; }
}

var moarPizza = session.Get<Pizza>(moarPizzaId);
person.Pizzas.Add(moarPizza);
await session.Update(person);
// FAILS in same session.  Succeeds in new session
Assert.True(person.PizzaIds.Contains(moarPizzaId));

[zeitlerc]

This is fixed by #77 if session.Update was called. If the Ids are accessed before session.Update is called, they will still return outdated information