Function appendChildren

docs/app/js/sanddance-app.js:6691–6693

(parentElement, children)

    else parentElement.appendChild(document.createTextNode(child.toString()));
}
function appendChildren(parentElement, children) {
    children.forEach((child)=>addChild(parentElement, child));
}
function isElement(el) {
    //nodeType cannot be zero https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeType
    return !!el.nodeType;