Today BY BILLY COLLINS If ever there were a spring day so perfect, so uplifted by a warm intermittent breeze that it made you want to throw open all the windows in the house and unlatch the door to the canary's cage, indeed, rip the little door from its jamb, a day when the cool brick paths and the garden bursting with peonies seemed so etched in sunlight that you felt like taking a hammer to the glass paperweight on the living room end table, releasing the inhabitants from their snow-covered cottage so they could