By Simon Evans MANCHESTER, England (Reuters) -Cristiano Ronaldo answered all the questions about his continuing value to Manchester United with a superb hat-trick to secure a 3-2 win over Tottenham Hotspur in an entertaining Premier League contest on Saturday. Just six days after doubts were raised about his injury absence for the Manchester derby and at the end of a week marked by tabloid speculation over his relationship with interim manager Ralf Rangnick, the 37-year-old delivered a reminder of just why United chose to bring him back to Old Trafford. The five-times Ballon d’Or winner headed…