NEW YORK/ WASHINGTON, Feb 16 (Reuters) - A U.S. federal judge in Pennsylvania ordered the National Park Service on Monday to reinstall a slavery exhibit at a Philadelphia historic site, pending the outcome of litigation after the city sued the government over its removal. The exhibit was dismantled and removed last month in response to President Donald Trump's claims, rejected by civil rights groups, of an "anti-American ideology" at historical and cultural institutions. "The government claims it alone has the power to erase, alter, remove and hide historical accounts on taxpayer and local government-funded monuments within its control," U.S. District...