(Adds fifth para) By Tony Jimenez TROON, Scotland, July 12 (Reuters) - A British Open caddie was taken to hospital after being hit on the head by a stray shot from former world number one Vijay Singh during a practice round on Tuesday. William Ciplinski, bagman for American veteran Marco Dawson, was lying flat out on a golf buggy when he was initially taken to the medical centre at Royal Troon. Ciplinski was standing on the eighth green when he was struck by an errant tee shot from Fijian Singh on the seventh hole. More...