NIAMEY (Reuters) – Four Frenchmen held hostage within the Sahara desolate tract by al Qaeda-linked gunmen for three years left Niger on a French executive airplane on Wednesday morning. The men, who were kidnapped in 2010 whereas working for French nuclear group Areva and a subsidiary of building workforce Vinci in northern Niger, have been freed on Tuesday after secret talks. A Reuters correspondent at Niamey airport said the four men boarded the jet with two French ministers, together with Foreign Minister Laurent Fabius, dispatched to pick out them up. “I’m more than pleased. …