In one volume, the screenplays to two contemporary classics, directed by Richard Linklater, and starring Ethan Hawke and Julie Delpy, about the immediate and life-altering attraction between two strangers.    On a train from Budapest to Vienna, Jesse, a young American student, at the end of a romance and his European trip, meets Celine, a young French woman. They are immediately attracted. Despite knowing this may be the only time they will see each other, in the next few hours in the city of Vienna, they share everything and promise to meet again.     Nearly a decade later, Jesse, now a novelist on a publicity tour, sees Celine in a bookstore in Paris. Again their time is short, and they spend it reestablishing the connection they experienced on their first meeting. Romantic, poignant, understated, and often profound, these two screenplays are sure to become classics in their own right.