MINISERIES PREMIERE: This new three-part dramatization of the Daphne du Maurier thriller, presented by Acorn TV and doled out in consecutive weekly installments each Monday on the Acorn TV website beginning today, stars Jessica Brown Findlay, whose unexpected departure as Sybil rocked fans of Downton Abbey. Here, in this revisiting of the same plot turned into a 1939 Alfred Hitchcock movie, she plays Mary Yellan, a woman who grew up on a farm and, after her parents died, traveled to Cornwall to