In periods when the world and its inhabitants seem too vicious to bear, some people find themselves drawn magnetically to what might be called feel-bad entertainment. I mean the sort of book, song or show that massages your anxiety the way your tongue might insistently probe an abscessed tooth. If that's the way you're feeling at the moment - and why do I suspect that's the case? - you may well find pleasurable pain in Robert Icke and Duncan Macmillan's discombobulating stage adaptation of George Orwell's '1984,' which opened on Thursday night at the Hudson Theater. But it will be pain of a different order (possibly involving nausea) from the empathetic kind you experience reading Orwell's ever-engrossing book.