A teenager walking home from a party was fatally shot near West 127th Street and Adam Clayton Powell Jr. Boulevard around 2:30 a.m. yesterday morning. Nathan Allsbrook was shot in the shoulder, and the bullet traveled into his heart. Police suspect Allsbrook was was hit by a stray bullet. The NY Times says the shell casing "was found a substantial distance" from where Allsbrook had been standing and the Daily News suggests the shot was......