By Alan Smith Paris is promising an opening ceremony like no other. But 100 days out, president Emmanuel Macron has finally admitted that Olympics organisers have relocation plans in place should a viable terror threat be made. For now, the intention is for a flotilla carrying 10,000 athletes to make a six-kilometre journey along the Seine. A boat for each nation will depart Austerlitz bridge before ending up at the Trocadero – taking in many of the city’s most famous landmarks. Along the quays more than 300,000 spectators will gather – a huge audience but still less than half of what was init…