Several years ago, a major New York City depart- ment store ran a humorous ad disparaging knit¬ting as an activity for grandmothers. The response? Ardent members of New York's Big Apple Knitting Guild took up their yarn and needles and staged a knit-in. To demonstrate that knitting isn't an activity limited to the rocking chair set but rather is an alive and timely art, a group of knitters of …