change logic in widget.php so external URL's open in a new tab

ext_url_widget.php

//adding markup to the logic on line 81 of widget.php
$registration_url = $event->externalURL != '' ? '<a target="_blank" href="' . $event->externalURL . '">' : '<a href="' . espresso_reg_url($event->id) . '">';

//later, on line 130, the a tag needs to be removed from the markup:
<p><?php echo $registration_url; ?><?php echo stripslashes_deep($event->event_name) ?> - <?php echo event_date_display($event->start_date) ?></a>