* [INODE,FIX] Making use of the rewritten ASSOC_EXT, the updating of association lists for Ps->Ss and Ps->(POs->Ss) now works.
Several important fixes for asserting the identity hierarchy.

* [SC] Simplified assert_inodes/4 and run_experiment/4 (removed one parameter).
* [INODE,FIX] The numer of identity pairs characterized by the collection of identity sets was incorrect: identity pairs `X-Y` and `Y-Z` represent an identity set `{X,Y,Z}` which describes 3 (not 2) identity pairs.
* [INODE,FIX] Clearing the database in between tests did not work: retract does not work for pradicate name + arity notation.
* [INODE,FIX] The number of pairs in a set was calculated incorrectly using `aggregate/3`, use `aggregate_all/3` instead.
* [INODE,FIX] The search for edges between inodes was incorrect (regression due to incomplete replacement of `strict_sublist/2` with `ord_strict_subset/2`.