Louis Armstrong believed he was born on July 4, 1900. Subsequent historical research might suggest otherwise, but why get hung up on mere details? A true Horatio Alger figure, who revolutionized both instrumental and vocal music, and represented America abroad as the unofficial “Ambassador Satch,” it is a symbolically fitting birthday for Armstrong, so I always listen to his music over the holiday. This Fourth of July you can see him on the big screen when the Lincoln Center’s Walter Reade scree