NOUAKCHOTT, Mauritania — Funeral services were held June 30 for a U.S. teacher in Mauritania who was shot dead by Islamic extremists for spreading Christianity. Christopher Leggett, 39, of Cleveland, Tenn., was killed June 23 in front of the language and computer school he operated in Nouakchott, the capital city. Al-Qaida in the Islamic Maghreb, North African unit of the…