does the chain group have any ready-to-execute scripts?
function check_chain_group_scripts_ready(chain_group) {
		var any_scripts_ready = false;
		for (var i=0; i<chain_group.scripts.length; i++) {
			if (chain_group.scripts[i].ready && chain_group.scripts[i].exec_trigger) {
				any_scripts_ready = true;
				chain_group.scripts[i].exec_trigger();
				chain_group.scripts[i].exec_trigger = null;
			}
		}
		return any_scripts_ready;
	}