Conservative columnist Charles Krauthammer sat down with Fox News’ Bill O’Reilly and opined that Newt Gingrich won last night’s debate — in fact, he “won big.” Krauthammer criticized Mitt Romney‘s mediocre debate performance and was incredulous at how the former Massachusetts Governor wasn’t prepared for a question on his tax returns. “How could he not have prepared a nice short succinct humane answer about what he did at Bain?” Krauthammer perplexedly exclaimed. “He didn’t really have that — he kind of stumbled around.” RELATED: Rick Perry Challenges Romney: ‘Mitt, We Need For You To Release Your Income Tax’ O’Reilly wondered...