Add checkbox for previewing articles in new tab

Author: thiagogq

settings.html

@@ -245,6 +245,8 @@
             <label for="rss-for-mainpage">Generate RSS for the Main Page</label><br/>
             <input type="checkbox" id="rss-for-sections">
             <label for="rss-for-sections">Generate RSS for Section Pages</label><br/>
+            <input type="checkbox" id="preview-in-new-tab">
+            <label for="preview-in-new-tab">Preview articles in a new tab</label><br/>
           </div>
           <br/><br/>
           <span>View and edit the &nbsp;&nbsp;<a id="open-rss-modal" class="button" href="#">RSS templates</a></span>