Tens of thousands of protesters, chanting "Enough is Enough," joined the children's crusade in downtown LA today to end gun violence. "Hey hey NRA, how may kids did you kill today?" they chanted behind a giant March for Our Lives banner that stretched sidewalk-to-sidewalk across 6th Street. 'Hey hey, ho ho, the NRA has got to go" their young voices rang out against the buzz of police and news helicopters hovering overhead. Both celebratory and serious, the marchers…