A faint but strong heart beats for 18th and Vine. That much was obvious last Tuesday night, when a crowd packed the lobby of the Gem Theater to take part in what might sound like one of the most boring activities of good citizenship: a city planning meeting. At least a hundred people showed up to hear what City Hall had in mind for the district -- and listening to City Hall talk about 18th and Vine can be emotionally risky. After all, it's been a long time since Emanuel Cleaver's administr