Calendar summer is roughly three months long, but NFL summer is a fraction of that, and soon, it will be over. Two weeks from today, every team’s veterans will have reported to training camp. That’s data that can be found in our list of the camp reporting dates and locations, which the NFL furnished on Monday. Take a look at the list. It’s interesting stuff. For instance, Baltimore, Buffalo and San Francisco’s rookies report on Wednesday. Wednesday! And it’s neat to see the Steelers still holding camp at Saint Vincent College, where they have done their summer work since 1967. Think about it — visitors to the 1974, 1975, 1978, 1979, 2005 and 2008 camps in Latrobe, Pa. saw a future Super Bowl champion starting to jell. Mainly, though, paging through the training camp information at this point of July, on the doorstep of baseball’s all-star game and the British Open, drives home the feeling that pro football’s work will soon begin again in earnest. Think of it this way: if the NFL were just a little town that put on a summer fireworks display . . . well, all that would be left now was the smoke from the grand finale and the sound of people gathering their belongings and shuffling to their cars. The NFL, of course, is anything but diminutive. And the fireworks are just about to start.