[enh] linkable search url display

searx/static/css/style.css

 #suggestions span { display: block; margin: 0 2px 2px 2px; padding: 0; }
 #suggestions form { display: block; }
 #suggestions input { padding: 2px 6px; margin: 2px 4px;  font-size: 0.8em; display: inline-block; background: #3498DB; color: #FFFFFF; border-radius: 4px; border: 0; cursor: pointer; }
+#search_url { margin-top: 8px; }
+#search_url input { border: 1px solid #888888; padding: 4px; color: #444444; width: 20em; display: block; margin: 4px; }
 
 #preferences {
     top: 10px;

searx/templates/results.html

         </div>
         {% endif %}
 
+        <div id="search_url">
+            {{ _('Search URL') }}:
+            <input type="text" value="{{ base_url }}?q={{ q|urlencode }}&pageno={{ pageno }}" readonly="" />
+        </div>
         <div id="apis">
         {{ _('Download results') }}
         {% for output_type in ('csv', 'json', 'rss') %}

searx/webapp.py

         selected_categories=search.categories,
         paging=search.paging,
         pageno=search.pageno,
+        base_url=get_base_url(),
         suggestions=search.suggestions
     )