ENGLEFIELD, England — Pippa Middleton, radiant in a custom-made wedding gown, married a wealthy financier Saturday as two likely future British kings and other members of the royal family, including her sister, looked on. In what was seen by many as the society wedding of the year, Middleton and hedge fund manager James Matthews said their vows in a ceremony at St. Mark’s Church in Englefield, west of London. Before the wedding, a crowd of well-wishers and reporters gathered outside the church grounds, hoping for a glimpse.