CHARLOTTE, N.C. — For gay and lesbian delegates to the Democratic National Convention, this week's gathering offers a momentous opportunity to vote, for the first time in history, on a party platform that calls for legalizing same-sex marriage. "This is historic," said Rich Bailey of Austin, a gay man who has been politically active for 26 years. "It's my first national convention, and I'm really excited I get to go to this one, especially one where we have an opportunity to vote on this plank." Delegates Sue Spell and Carol Cappa from Fort Worth, together for 11 years, have discussed...