By Brendan O’Brien and Tom Polansek HIGHLAND PARK, Ill. (Reuters) -The man accused of opening fire with a rifle from a rooftop onto a crowd of people watching a July Fourth parade near Chicago, turning the holiday celebration into another national tragedy, was charged on Tuesday with seven counts of first-degree murder. If convicted, the suspect, 21-year-old Robert E. Crimo III, would face a maximum sentence of life in prison without the possibility of parole, Illinois states attorney Eric Reinhart said in announcing the charges at a news conference. Reinhart said the first-degree murder charg…