"BTS 2.0 is just getting started!" J-Hope declared as he stood alongside the other six members of the world's biggest band. It was 21 March and, after a long break, J-Hope, RM, Suga, Jin, Jimin, V and Jung Kook had taken to the stage again - silhouettes against an arch of LED screens framing the historic gate to the royal palace in Seoul, as screaming crowds stretched for blocks. Tens of thousands turned up to watch and more than 18 million people live-streamed the one-hour show - a slick