The online photo show “Y/OUR Denver” is a lot of good things rolled into one: a contemporary art exhibit; an armchair tour of a city growing at warp speed; a primer on some of our best architecture; and nothing less than a 100-year history lesson on civic progress. And on top of all that, it’s probably the easiest high-quality cultural offering to consume this year, since its exists on the website of the Colorado Photographic Arts Center.