The anonymously written 1592 play Arden of Faversham is just the sort of thing that Red Bull Theater specializes in: plays of Shakespeare’s contemporaries that have been overshadowed by the Bard. But even the best of Shakespeare needs pruning, and Arden has received a new adaptation by Jeffrey Hatcher and Kathryn Walat for artistic director Jesse Berger’s production. The result is a mixed bag: necessary condensation of characters and cutting obscure lines, but also some wholesale rewriting.