Remove the second of two duplicates, not the first.

This addresses the problem that variable orders may be switched.
Simpler PRINT-OBJECT.
FOFIFY needs to work with FOF objects, too, and in the same way as CNF objects.
UPDATE-INFERENCE-PARENTS for a TPTP-DB object.
Use POSITION-IF, and replace names (not indices).
Update RESTRICT-SOLUTION-TO-PROBLEM-LANGUAGE to account for change in formula annotations.