A Brookline resident is targeting next week’s Town Meeting as the launching pad for the impeachment of President Bush. Of course, it’s nonbinding. “I can no longer stay silent with the current administration,” said Jonathan Margolis, who vows to place the resolution before fellow voters. Town Meeting, a unique Yankee institution, is usually saved for tax hikes, water projects and new schools. Margolis said he’s dipping into national politics at the grassroots of democracy. It worked for our forefathers, he argues. “Town Meeting is a place where citizens can speak up,” he said. “The Revolution started this way - one...