Pianist Lawrence Cotton rightfully calls his band, which will be performing at the Satchmo SummerFest on Saturday, August 5, the Legendary Experience. Cotton, who will celebrate his 90th birthday on February 2, 2017, is definitely in that “legendary” number. First of all, he played, recorded and toured with the rhythm and blues star, the one-­of-­a-­kind Guitar Slim of 1954’s “The Things That I Used to Do” fame. Though Cotton wasn’t on the 45—none other than Ray Charles was at the piano—he to...