Hundreds of outraged Bay State students — saying they’re tired of active-shooter drills and mass-killing headlines — jammed the State House yesterday to demand stronger gun control, joining the national student walkout movement on their snow day.Throngs of students from at least 50 schools — including those in Somerville, Boston, Medford, Cambridge, Wellesley and Arlington — shouted “enough is enough” and wielded signs reading “fear has no place in our schools” and “protect our kids, not your guns.”