[enh] py3 compatibility

searx/engines/duckduckgo_definitions.py

@@ -1,10 +1,10 @@
 import json
-from urllib import urlencode
-from re import compile, sub
 from lxml import html
-from searx.utils import html_to_text
+from re import compile
 from searx.engines.xpath import extract_text
 from searx.engines.duckduckgo import _fetch_supported_languages, supported_languages_url
+from searx.url_utils import urlencode
+from searx.utils import html_to_text
 
 url = 'https://api.duckduckgo.com/'\
     + '?{query}&format=json&pretty=0&no_redirect=1&d=1'