Drones take to the skies in a display at the Ars Electronica festival in Linz, AustriaMartin HieslmairIn a disused mail sorting office in Linz, Austria, an industrial robot twice my height has got hold of Serbian-born artist Dragan Ilic and is wiping him over a canvas-covered wall. Ilic is clutching pencils, and as the robot twirls and dabs him against...