docs: function getHtmlFilenames (directory)
  {
    return fs.readdirSync(directory).map(function (file) {
      return path.join(directory, file);
    }).filter(function (file) {
      return fs.statSync(file).isFile();
    }).filter(function (file) {
      return path.extname(file).toLowerCase() == ".html";
    });
  }