add time range support for bing images

searx/engines/bing_images.py

 categories = ['images']
 paging = True
 safesearch = True
+time_range_support = True
 
 # search-url
 base_url = 'https://www.bing.com/'
 search_string = 'images/search?{query}&count=10&first={offset}'
+time_range_string = '&qft=+filterui:age-lt{interval}'
 thumb_url = "https://www.bing.com/th?id={ihk}"
+time_range_dict = {'day': '1440',
+                   'week': '10080',
+                   'month': '43200'}
 
 # safesearch definitions
 safesearch_types = {2: 'STRICT',
         '&ADLT=' + safesearch_types.get(params['safesearch'], 'DEMOTE')
 
     params['url'] = base_url + search_path
+    if params['time_range'] in time_range_dict:
+        params['url'] += time_range_string.format(interval=time_range_dict[params['time_range']])
 
     return params
 

tests/unit/engines/test_bing_images.py

         dicto['pageno'] = 1
         dicto['language'] = 'fr_FR'
         dicto['safesearch'] = 1
+        dicto['time_range'] = ''
         params = bing_images.request(query, dicto)
         self.assertTrue('url' in params)
         self.assertTrue(query in params['url'])