A judge entered a plea of not guilty on Nikolas Cruz's behalf as the teen was arraigned Wednesday in last month's massacre at a South Florida high school -- on the same day students across the country walked out of class to demand stricter gun laws because of the killings. A Broward County grand jury last week indicted the 19-year-old gunman on 17 counts of premeditated murder in the first degree and 17 counts of attempted murder in the first degree. Wednesday's plea in a Fort Lauderdale court came after Cruz's defense attorney told the judge that the teen was...