One swallow doesn’t make a summer, and I’m not sure if you can count four instances of a product as a trend, but it’s certainly an interesting thread at this year’s CES. At this year’s show, a quartet of companies are showing off urine analysis tools designed to be used at home by the general public. These are positioned as a natural evolution of the fitness tracker, a device you can use to keep an even closer eye on your health and fitness. Most of them are built for your toilet,...