[enh][mod] result handling refactor

Several changes has been made:
 - Parallel result merge
 - Scoring algorithm slightly changed (see result_score())
 - Proper Thread locking on global data manipulation

searx/tests/test_search.py

@@ -1,25 +1,10 @@
 # -*- coding: utf-8 -*-
 
-from searx.search import score_results
 from searx.testing import SearxTestCase
 
 
-def fake_result(url='https://aa.bb/cc?dd=ee#ff',
-                title='aaa',
-                content='bbb',
-                engine='wikipedia'):
-    return {'url': url,
-            'title': title,
-            'content': content,
-            'engine': engine}
+#  TODO
+class SearchTestCase(SearxTestCase):
 
-
-class ScoreResultsTestCase(SearxTestCase):
-
-    def test_empty(self):
-        self.assertEqual(score_results(dict()), [])
-
-    def test_urlparse(self):
-        results = score_results(dict(a=[fake_result(url='https://aa.bb/cc?dd=ee#ff')]))
-        parsed_url = results[0]['parsed_url']
-        self.assertEqual(parsed_url.query, 'dd=ee')
+    def test_(self):
+        pass