It’s time to dance the flamenco or tango — that is, if fashion designers have anything to do with it. Looks that recalled the costumes for those great Spanish dances were an important trend for spring, turning up in the form of everything from ruffled skirts — sometimes cut away to allow for high kicks — and off-the-shoulder blouses to dramatically frothy numbers that need practically nothing but a mantilla and pair of castanets to complete them.