Combinatorial statistics

Every combinatorial statistic in @enumeratio/statistics — a head applied to a carrier (Descents on a Permutation, LargestPart on an IntegerPartition). Each is a definition over the object, evaluable on any row of the matching collection. One head can be a different statistic on a different carrier, so it appears once per carrier. The FindStat ids are established by value — the definition evaluated on every object up to a size and matched by FindStat's finder — or recorded in the enumeratio catalog, and the tooltip says which.