A Halal Slaughterhouse Provides Nourishment for a Far-Flung Culture
Profile of American Halal Meat, Newark, NJ, slaughterhouse that is emblematic of growing presence of Muslims in America, now estimated to number more than seven million; it is one of region's biggest operations, shipping animals to butchers and restaurants as far as Philadelphia and Albany; slaughterhouse is drafty and damp, warmed by camaraderie and shared faith of those who work there; profiles of several key workers, and of overall operation; photos (M)