Improve the enQuery construct to use a class

[enrh]

Where I return my jQuery-like object I could instead reference a class here.

/**
 * Construct element for displaying the specified color.
 *
 * @param {string} input
 * @param {string|null} label
 * @returns {Object}
 */
function colordiv(
  input,
  label=null,
) {

  let element =
    $('<div/>').addClass(
      'encommon_colordiv');

  ...

  return element; }