HARARE (Reuters) - President Robert Mugabe told the U.S. ambassador to Zimbabwe to "go to hell" on Tuesday, after the envoy blamed the country's economic and political crisis on mismanagement and corrupt rule. State media said the ambassador, Christopher Dell, risked expulsion from the southern African country for his "undiplomatic" criticism of the government in a public lecture. The Zimbabwe Broadcasting Corporation (ZBC) said it had asked Mugabe for his reaction to the comments. "The president said the ambassador must go to hell. The president said: 'I cannot even spell the word Dell with a "D" but an "H" and...