Cops shot a knife-wielding maniac dead on a packed Midtown street yesterday after several officers drew their weapons and chased him at gunpoint through Times Square. “Shoot me! Shoot me!” the armed madman shouted at a crowd of more than 20 cops, who had followed him for several blocks and blasted him with pepper spray before cornering him on Seventh Avenue near West 38th Street, according to witness Robert James. The furious 51-year-old finally lunged at the officers with his 11-inch butcher knife, leading two cops to blast him in the torso, groin and arms at about 3 p.m., police...