By default, Base._edit first tests each property with getProperty, not to
modify the object when values don't change. Here, getProperty costs a lot
(in particular for categories) and rarely/never avoids the use of setters.

So here, the main gain is to do something like _edit(force_update=1).
As an additional small optimization, we directly use _setProperty instead of
_edit. We also stop copying int_index from the Amount Generator Line because
it's not useful enough:
- float_index may be used instead
- or dependency-based sorting is enough
- as a last resort, properties can be fetched directly from the causality
  value, or dynamically with asPredicate and mapped_value_property_list