Lee Hall: 'I'd fax Elton my lyrics " then he'd call me up and sing them down the phone'The moment we finished the film, we took it to the Cannes film festival. It was only a small screening and, at that point in 2000, no one had any idea how huge it would be. But Elton John saw it, loved it, and suggested a musical. The next thing I knew, we " Stephen Daldry, the director, and me " were flying out to his New York apa…