function normalize(a, dst) {
  dst = dst || new VecType(3);
  var lenSq = a[0] * a[0] + a[1] * a[1] + a[2] * a[2];
  var len = Math.sqrt(lenSq);

  if (len > 0.00001) {
    dst[0] = a[0] / len;
    dst[1] = a[1] / len;
    dst[2] = a[2] / len;
  } else {
    dst[0] = 0;
    dst[1] = 0;
    dst[2] = 0;
  }

  return dst;
}
Divides a vector by its Euclidean length and returns the quotient.
@param {module:twgl/v3.Vec3} a The vector.
@param {module:twgl/v3.Vec3} [dst] vector to hold result. If not new one is created.
@return {module:twgl/v3.Vec3} The normalized vector.
@memberOf module:twgl/v3