code: function addOutProperty(out, directory, extensions) {
  	out[directory] = {
  		extensions: extensions
  	};
  	Object.defineProperty(
  		out[directory],
  		'directory',
  		{
  			get: function () {
  				return Config.fileLoaderDirs[directory];
  			},
  			set: function (value) {
  				Config.fileLoaderDirs[directory] = value;
  			},
  			enumerable: true,
  			configurable: false
  		}
  	);
  	out[directory].directory = out[directory].directory || directory;
  }
docs: Add an output directory settings to the configuration.
  
  @param {Object}   out        The output configuration.
  @param {string}   directory  The directory setting key and default name.
  @param {string[]} extensions The file extensions.