NEW YORK — A new, troublesome topic hovered over the St. Patrick's Day Parade in New York this year: Britain's failed Brexit deal with the European Union that could squeeze Ireland's economy.But nothing could put a damper on the largest American celebration of Irish heritage on Saturday, with tens of thousands of marchers following a painted green line up Fifth Avenue for the six-hour procession.Kevin Coughlan, a 27-year-old spectator wearing pants with four-leaf clovers, [...]