At the Democratic National Convention in July, first lady Michelle Obama stated, “I wake up every morning in a house that was built by slaves.” Mrs. Obama has made similar comments in the past, as have others on Capitol Hill.Some have criticized Mrs. Obama’s statement, claiming that she was a “revisionist” or had deliberately misstated historical fact. Was the first lady correct? To borrow the theme from the “X-Files” television show, “The truth is out there.”The White …