This 1977 movie turned disco into a phenomenon, both musically and in terms of night life, and made a major, enduring movie star out of Karen Lynn Gorney. Just kidding on that last one – but she’s the female lead here, opposite John Travolta, who did launch a major, enduring movie career with this still-iconic role. And it’s a career that, almost 40 years later, is staying alive, staying alive…