Use "noreferrer noopener" for links that open in a new window

[asaage]

Add link-attributes to the default templates (see https://github.com/contao/core-bundle/commit/f9d13e22dc107ac691a60e64b93f75a69d75b57f)

occurrences:

• https://github.com/numero2/contao-storelocator/blob/master/templates/modules/mod_storelocator_details.html5#L40
• https://github.com/numero2/contao-storelocator/blob/master/templates/modules/mod_storelocator_infowindow.html5#L18
• https://github.com/numero2/contao-storelocator/blob/master/templates/modules/mod_storelocator_inserttag.html5#L15
• https://github.com/numero2/contao-storelocator/blob/master/templates/modules/mod_storelocator_list.html5#L61