MINNEAPOLIS — David Guy McKay walked out of the federal courthouse, felt the sting of a 4-degree temperature and a wicked northwest wind and declared how great it felt. McKay, 23, of Austin, had reason to feel elated. He was getting his first taste of freedom an hour after a judge declared a mistrial when the jury deadlocked on charges that he made and possessed Molotov cocktails during last summer's Republican National Convention in St. Paul, Minn.