[ test ] PartialOrd: redid Ulf's 903ca3b371848ed8c27ef6fb162aad79c1d2bf3d on branch maint-2.4.0
undo change of Makefile
Merge branch 'maint-2.4.0'
[ test ] new property: idempotent
[ issue 1222 ] fixed: seqPO needs to be orPO in PO for tuples
[ util ] Direct implementation of Utils.PartialOrd.leqPO
[ test ] Utils.PartialOrd.orPO and seqPO are idempotent
Merge branch 'maint-2.4.0'