These days, thanks to medical science and advances in health care, people are living longer.Today there are a lot more senior citizens among my friends who have not only begun to resemble their parents but are now frequently using such expressions as “back in the day,” “the good old days,” “when I was your age” and “you should have been there.”Well, it’s true. Back in the day, the 1930s through the ’40s, in Chicago, close to 100 “Black and tan” integrated African-American jazz and blues venues were located in the …