By Andrew MacAskill and Lindsay Dunsmuir EDINBURGH (Reuters) – King Charles and his siblings held a silent vigil at the side of their mother Queen Elizabeth’s coffin as it lay at rest in Edinburgh’s historic cathedral, with thousands queuing for hours to pay their respects to Britain’s longest-serving monarch. With their heads bowed, Charles, wearing a kilt, alongside sister Princess Anne and brothers Princes Andrew and Edward, stood solemnly for 10 minutes next to the oak coffin, draped with the Royal Standard of Scotland with a wreath of white flowers and the Crown of Scotland. They left the…