NEW YORK -- At 47, Haskell Wexler was one of the nation's most successful cameramen. He'd won an Academy Award in 1966 for his work on Mike Nichols' "Who's Afraid of Virginia Woolf?" He had been the cinematographer on films by Elia Kazan ("America, America"), Joseph Strick ("The Savage Eye"), Tony Richardson ("The Loved One") and Norman Jewison ("In the Heat of the Night," "The Thomas Crown Affair"). But he wanted to direct his own movie. And last summer he came to Chicago to do that. The result is "Medium Cool," a movie unlike anything you have seen and possibly unlike anything you want to see. It is likely to be this autumn's most controversial film.