The world needs a new Beatles documentary like it needs another garbage gyre in the Pacific Ocean, but The Beatles: Eight Days a Week plays it smart by selecting a single lane of the Fab Four’s sprawling saga and following it from start to finish. Director Ron Howard’s slick but enjoyable movie focuses on the group solely as a touring and performing entity during the Beatlemania years of the early and mid 1960s. It didn’t take long for John, Paul, George, and Ringo to become fed up with live performances, and the Beatles had switched to a recording-studio-only entity by the release of 1967’s Sgt. Pepper’s Lonely Hearts Club Band…