[ehn] Add a 'featured result feature'm putting on top of the reasults ddg definitions and wikipedia (ugly html / css)

searx/templates/result_templates/videos.html

 <div class="result">
-  
   {% if result['favicon'] %}
   <div style="float:left; margin:2px;">
-    <img width="18" height="18" src="static/img/icon_{{result['favicon']}}.png" alt="{{result['favicon']}}.png" title="{{result['favicon']}}.png" />
+    <img width="18" height="18" src="static/img/icon_{{result['favicon']}}.ico" alt="{{result['favicon']}}.ico" title="{{result['favicon']}}.ico" />
   </div>
   {% endif %}
 
-
     <p>
       <h3 class="result_title"><a href="{{ result.url }}">{{ result.title|safe }}</a></h3>
       <a href="{{ result.url }}"><img width="300" height="170"  src="{{ result.thumbnail }}" title={{ result.title }} alt=" {{ result.title }}"/></a>

searx/webapp.py

             result['pretty_url'] = result['url']
 
         for engine in result['engines']:
-            if engine in ['wikipedia', 'youtube', 'vimeo', 'soundcloud', 'twitter']:
+            if engine in ['wikipedia', 'youtube', 'vimeo', 'soundcloud', 'twitter', 'stackoverflow']:
                 result['favicon'] = engine
             if engine in ['wikipedia', 'ddg definitions']:
                 featured_results.append(result)