[simple theme] rework select; add safesearch to search and replace / with › in article url

* rework selection UI in pref (fix based on: 78643e9f43)
* moved search filters underneath categories
* cut params from url and replace / with ›
* make h3 and url in article bigger
* add safe search select to search filter (this will not override settings and only be valid while on result page in a session)
* make search form button not overlap each other when js is disabled
* 1rem padding around preview image and thumbnail in default article template

searx/static/themes/simple/src/js/main/search.js

@@ -98,6 +98,7 @@
         return false;
       });
 
+      searxng.on(d.getElementById('safesearch'), 'change', submitIfQuery);
       searxng.on(d.getElementById('time_range'), 'change', submitIfQuery);
       searxng.on(d.getElementById('language'), 'change', submitIfQuery);
     }