Flying a drone is kind of like driving a car that only has a windshield. You can only look in one direction at a time, and when the drone gets out of visual range, the user is left with a single view through the lens of a camera. Hivemapper, a company that just raised a $3 million Series A led by Spark Capital, is looking to make that a bit safer. Hivemapper has mapped over 20 million building boundaries, more than 10 million building heights, and 15 million points of interest all plotted on a 3D map. Plus, the app...