Several major companies world-wide are feverishly racing to become the first to offer a flying technology that will whisk you above the crowded gridlocked streets of a city to the airport or theater or shopping center. It may sound like Back to the Future Part Gazillion, but the technology is almost in place to begin liftoff. eVolo, a German company, is working on a multicopter that features twenty propellers to lift you up and over the ground to your destination. Each propeller is controlled by a separate computer system. EHang…