(Adds quotes, detail) VATICAN CITY, Feb 28 (Reuters) - Pope Benedict, addressing cardinals on his final day in office, called on Thursday for the Roman Catholic Church to unite behind his successor and pledged his own "unconditional" obedience to the next pontiff. "I will continue to be close to you in prayer, especially in the next few days...as you elect the new pope to whom I today declare my unconditional reverence and obedience," he said.