improved correctness of handling of higher-order occurrences of "Not" in new Metis (and probably in old Metis)
improved correctness of handling of higher-order occurrences of "Not" in new Metis (and probably in old Metis)

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle