Simplified proof of ord_iso_image_pred using bij_inverse_ss. Replaced not_well_ord_iso_pred_lemma by much simpler well_ord_iso_subset_lemma. Simplifed proof of well_ord_iso_unique_lemma using well_ord_iso_subset_lemma.
Simplified proof of ord_iso_image_pred using bij_inverse_ss.
Replaced not_well_ord_iso_pred_lemma by much simpler well_ord_iso_subset_lemma.
Simplifed proof of well_ord_iso_unique_lemma using well_ord_iso_subset_lemma.

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