v2.1.0

• Feature: Add support for binding custom functions to any key code.
  (#70 by @clue)

  $readline->on('?', function () use ($stdio) {
      $stdio->write('Do you need help?');
  });

• Feature: Add addInput() helper method.
  (#69 by @clue)

  $readline->addInput('hello');
  $readline->addInput(' world');