"Thus, “not with a bang, but a whimper,” the plurality discards a landmark case of the last generation, an casts into darkness the hopes and visions of every woman in this country who had come to believe that the Constitution guaranteed her the right to exercise some control over her unique ability to bear children…For today, at least, the law of abortion stands undisturbed. For today, the women of this Nation still retain the liberty to control their destinies. But the signs are evident and very ominous, and a chill wind blows."