Clinton promises 'clear-eyed' vision, says Trump cannot be trusted

By John Whitesides and Amy Tennery PHILADELPHIA (Reuters) - U.S. presidential candidate Hillary Clinton said on Thursday the challenges facing Americans demand steady leadership and a collective spirit, contrasting her character with what she described as a dangerous and volatile Donald Trump. In the biggest speech of her more than 25-year-old career in the public eye, Clinton accepted the Democratic presidential nomination for the Nov. 8 election with a promise to make the United States a count