I've been watching a lot of Seventies fare lately, and have discovered some real gems and the occasional dud ("The Seven-Ups," a limp attempt to carry on the "French Connection" franchise with a tragically wasted Roy Scheider, comes to mind). I'll start off the "gems" discussion with "Straight Time," a 1978 film starring Dustin Hoffman as an ex-con named Max Dembo who has some muddled good intent…