NEW YORK — The Europeans have hit town with their early spring collections, which zero in on the waist. Attention is held high with buttons, plunging necklines and Empire shapes. Louis Feraud does a soft fluid dress with a draped bodice, while Karl Lagerfeld adds an Empire waist to a slip shape and matching jacket for Chloe. And for his signature collection, Lagerfeld emphasizes shoulders with such details as pads and seams on jackets and dresses. Meanwhile, at Christian Dior, Gianfranco Ferré favors softly tailored suits.