The Poor Boy's Game by Dennis Tafoya Minotaur Books, $25.99, 322 pages, ISBN 978-1-250-01953-0 Philadelphia, one of the oldest cities in America, has been the background for innumerable dramas from the Continental Congress to the signing of the Declaration of Independence to who-knows-how-many Rocky movies. It's the fourth largest city in the United States, a one-time capitol of the U.S. as well as a cultural and financial center. A