[mod][fix] using base_url instead of hostname in settings.py

searx/settings.py

 
 categories = {} # custom search engine categories
 
-hostname = None # domain name or None - if you want to rewrite the default HTTP host
+base_url = None # "https://your.domain.tld/" or None (to use request parameters)

searx/webapp.py

         method = 'get'
     if request.is_secure:
         scheme = 'https'
-    if settings.hostname:
-        hostname = '{0}://{1}/'.format(scheme,settings.hostname)
+    if settings.base_url:
+        hostname = settings.base_url
     else:
         hostname = url_for('index', _external=True, _scheme=scheme)
     ret = opensearch_xml.format(method=method, host=hostname)