As the Democratic National Convention in Denver gets closer, I'm sure we'll be hearing more about the diehard Hillary Clinton supporters who just can't admit that the war is over.Civil wars are always the most hurtful, and the Democratic primary battle between Barack Obama and Clinton sometimes strayed into that category of conflict. Although Obama and Clinton made up months ago, there is a small number of Hillary Holdouts who keep up the fight. It's hard to know just how many holdouts there really are. One group is called 18 Million Voices, which tries to advance the idea that all …