It rained a little on Broadway this week with the passing of Barbara Cook, a legend of the Broadway musical whose clarion soprano and boundless emotion took songs into the outer stratosphere. Cook, who has been a presence on the Broadway scene since the 1950s in both musicals and concerts, died on August 8 at the age of 89 after a long illness. Her legions of fans are mourning the loss of the great lady who, among myriad roles, originated the role of Marion Paroo in the 1957 production of The Music Man.