TRENTON -- The alleged gunman who was cut in half by an enraged father’s SUV Sunday was an escapee from an East Orange halfway house, police said yesterday. Police confirmed the identity of the dead suspect as Jose Alvarez, of Trenton, who would have celebrated his 20th birthday yesterday. Police said Alvarez was mowed down by Robert O’Neal, 54, in his Dodge Durango Sunday night, following an alleged robbery, shooting and car chase that ended with Alvarez killed along a southbound lane of Route 29. The identity of the dead suspect was just one of the new details which emerged...