AC-FOVE: Generalized Aggregation Parfactor Split on A/t

* AggregationParfactor: split on A/t
* Pool: correction on test variables

The method is working (apparently), but it definitely does not look
good. There are lots of casts (explicit and implicit), so I should
change it later.
AC-FOVE: Generalized Aggregation Parfactor Split on X/A

* GeneralizedAggregationParfactor: split on X/A