Also: U.S. Reggae acts swarm into Philly By Denny Dyroff, Staff Writer, The Times The legendary Al Kooper plays a rare show at the Sellersville Theater, Oct. 22. There are only a few artists in the realm of rock music who genuinely deserve to be called legends. Al Kooper is one of them. Kooper, who will perform on October 22 at the Sellersville Theater (24 West Temple Avenue, Sellersville, 215-257-5808, www.st94.com),...