WASHINGTON - They came by the hundreds, from Florida and Ohio, New York and Texas, passing through the same entrance at the U.S. Holocaust Memorial Museum where two days earlier security officers shot a man who had gunned down one of their own. The museum was closed Thursday in honor of Stephen T. Johns, who died from his wounds, and an avowed white supremacist has been charged. For many visitors, the reopening Friday was an opportunity to make a statement of defiance against intolerance.