The late, great director Robert Altman made some brilliant movies (Nashville, anyone?). He also made some unbelievably crappy ones (Pret-a-Porter). But the Brattle is here to sort the wheat from the chaff and to bring you the best of Robert Altman - at least the '70s Altman, anyway - all week long. Movie buffs, fill out your calendars! Tonight M*A*S*H (1970), 4:30, 7:00 People are so used to Alan Alda as Hawkeye that it's a......