title: Coloring faces of a Three.js BoxGeometry
body: <p>I saw some solutions that accessed the THREE.BoxGeometry faces like that:</p>
  <pre><code>var geometry = new THREE.BoxGeometry(n,n,n)
  let faces = geometry.faces;
  for (let face of faces) {
    face.color.set(Math.random() * 0xffffff);
  }
  </code></pre>
  <p>But it seems that the <code>faces</code>-array doesn't exist in the current Three.js version r129 (<code>Uncaught TypeError: faces is not iterable</code>).</p>
  <p>How can I achieve an easy coloring of the six cube faces?</p>