SAN DIEGO (Reuters) - A radical environmental activist has been indicted by a federal grand jury for demonstrating how to build a firebomb in a speech just 15 hours after a fire that his group claimed responsibility for destroyed a large apartment complex being built nearby. Rodney Adam Coronado, a 39-year-old member of the Earth Liberation Front, was indicted on a charge of giving instructions on how to build a destructive device, which carries a maximum sentence of 20 years in federal prison. The indictment was unsealed on Wednesday. The law under which he was charged has been used just...