public void Register(IAutoupdateableGameActor actor, int timePeriod = 1)
{
if (actor == null)
throw new ArgumentNullException("actor");
if (timePeriod <= 0)
throw new ArgumentOutOfRangeException("timePeriod", "Update period has to be larger than zero.");
Contract.EndContractBlock();
m_register[timePeriod].Add(actor);
}