As I have frequently noted in the past, one of my most memorable moments in theater was April 6, 1968, when I was attending a touring production of “Mame” at the Shubert Theatre following the assassination of Martin Luther King Jr. and the city was torn by riots.As I sat in the darkened half-full theater, I could literally feel the fear and trepidation from many of the audience members, who, against their better judgment, had come to the Loop for the performance that night.But as the bright sounds of Jerry …