MADRID (Reuters) - Spain said on Thursday it had arrested a Moroccan man suspected of heading two al Qaeda-linked cells and helping men involved in the 2004 Madrid bombings flee the country. In an Interior Ministry statement, the man was named as Omar Nakhcha, the alleged ring-leader of two cells believed to have recruited Islamist fighters for Iraq. The units were dismantled by police earlier this week and 20 people were arrested. Nakhcha, 23, was arrested in the northeastern province of Barcelona. Larbi Ben Sellam, a suspected Islamist militant arrested in June last year, told police that Nakhcha helped three...