Paul O’Connor found more than he expected in a new biography of General Custer. Reviewed by Paul T. O’Connor CUSTER’S TRIALS: A LIFE ON THE FRONTIER OF A NEW AMERICA. By T.J. Stiles. Books on Tape. Read by Arthur Morey. 23 hours, 42 minutes. $95. Also available in hardcover. Knopf. $30. Authors of historical fiction…