Photochemical and non-photochemical "A-D-Secocorrin-AEcorrin-Cyclizations of 19-Carboxy and 19-Formyl-1-Methylidene-1, 19-Secocorrinates-Decarboxylation (and Deformylation) of Nickel (II) - 19-Carboxy-(Resp 19-Formyl)-Corrinates