LIKE SARAH PALIN, BILL COSBY JUST keeps on talking. He has shown up yet again with more comments lately on cable news, and on the lucrative lecture circuit, continuing to malign and slander African Americans (witness his latest middlebrow, psychobabble Walmark book, "Come on, People: On The Path From Victims to Victors" another mediocre tract contemptuous of real socio-political causality and of real material conditions faced by Afric