George and Amal Clooney have just pledged $500,000 to help underwrite the efforts of survivors of the mass shooting at Marjorie Stoneman Douglas High School in Parkland, FL, to protest for meaningful gun control. These young people — who made a powerful plea on CBS’ Face the Nation on Sunday and in other places — seem potentially to be the lightning rod that has been lacking in the attempt to hold responsible federal lawmakers taking vast sums from the NRA and refusing to…