U2 set the scene for something a little bit special last night with the words ‘We’re gonna try a few songs from that time… we’re taking requests in Sydney..’ And with that we had the inimitable opening bars of All I Want Is You, played live for the first time since the Vertigo stop in Honolulu four years ago this month – and this Sydney audience joined in like their very lives depended on it. The super-slow ending, with Bono on harmonica while the audience…