Photo by Calvin E. Burdick, Jr.The 1960s in Houston still mostly exist in black and white....except in the photos of Calvin E. Burdick, Jr. He was an inveterate photographer whose son, Josh, offered us some shots for an item we did on the Astrodome documentary that's being made.We asked him to dig through his Dad's slides for some more scenes from the city's past. He found a time when downtown was still a thriving destination of locally owned stores, where people gathered for big events like a p