The arrival of Shear Madness in New York comes 36 years after the runaway hit opened in Boston. Since then, other editions have taken up residence in other cities, and inevitably the suspicion arises that the lengthy delay bodes a show that might not meet New York’s high standards. Happily, the lunatic confection at New World Stages indicates the opposite: all those years have helped create an indestructible engine for laughter that should keep its cast bankrolled for quite some time.