I will never forget the night of Saturday, April 6, 1968. Two days earlier on April 4, civil rights leader Martin Luther King Jr. had been assassinated and riots were erupting in African-American communities in cities throughout nation.Chicago was getting its share and people were warned against going into the Loop. But I was determined to go. I had tickets for “Mame,” Jerry Herman’s Tony Award-winning musical which was then making its initial touring company performance at the formerly named Shubert …