Add IEntity.Initialize<T>()
Add IEntity.Initialize<T>()

This replaces the pattern

  T data;
  if (entity.ContainsData<T>() == false) {
    data = entity.AddData<T>();
  }
  else {
    data = entity.Modify<T>();
  }

with

  T data = entity.Initialize<T>();

jacobdufault/forge,jacobdufault/forge