PARIS — Forget pistols at dawn: Try macaroons at high noon. There’s a pastry war raging, pitting 140-year-old institution Ladurée against Pierre Hermé, a hot newcomer described as the "Picasso of pastry." Long lines in front of the shop Hermé opened on Rue Bonaparte last fall are the norm for those addicted to his passion fruit macaroons. But Ladurée is firing back with seasonal macaroon flavors of its own and plans to open in New York and Japan, where Hermé has outposts and, this month, just up the road from Hermé’s own Parisian shop. Here, the latest from the battlefront."