Photochemical Nitration by Tetranitromethane. Part XXII. Adducts as Precursors of Nitro Substitution Products from the Photolysis of 1-Methoxynaphthalene--Tetranitromethane, Dehydrodimer Formation and the Regiochemistry of Trinitromethanide Ion Attack on the Radical Cation of 1-Methoxynaphthalene.