Add a plain text field type

I would really like to see an even simpler field type called 'Plain text' (probably using short values - varchar(255) for now) that we could easily extend for other field type like email, phone, and color to use for storage and default formatters. So rather than implementing all the hooks for each field, it would be nice to be able to do this:

// Note this is an overly simplified verison.
class FieldMail extends FieldPlainText {
  public function getWidgetForm() {
    $form = parent::getWidgetForm();
    $form['value']['#type'] = 'mail';
    return $form;
  }
}

Related:
#1696946: Rename field modules to [type]_field