Despite an injury sustained by star Andy Karl on April 14 and the cancellation of the April 15 matinee, the new Broadway musical Groundhog Day will open as planned on April 17. Previews began at the August Wilson Theatre on March 16. Groundhog Day features a book by Danny Rubin (who cowrote the screenplay) and a score by Matilda genius Tim Minchin. Matthew Warchus directs with choreography by Billy Elliot …