extend blacklist/whitelist syntax (#2025)

Each entry in such a list can now also include a subcategory
'<category>:<subcategory>'
and it is possible to use '*' or an empty string as placeholder
'*:<subcategory>', ':<subcategory>', '<category>:*'

For example
  "blacklist": "imgur,*:tag,gfycat:user" or
  "blacklist": ["imgur", "*:tag", "gfycat:user"]
will filter all 'imgur' extractors, all extractors  with a 'tag'
subcategory (e.g. https://danbooru.donmai.us/posts?tags=bonocho),
and all 'gfycat' user extractors.

test/test_job.py

@@ -37,6 +37,31 @@ class TestJob(unittest.TestCase):
             return buffer.getvalue()
 
 
+class TestDownloadJob(TestJob):
+    jobclass = job.DownloadJob
+
+    def test_extractor_filter(self):
+        extr = TestExtractor.from_url("test:")
+        tjob = self.jobclass(extr)
+
+        func = tjob._build_extractor_filter()
+        self.assertEqual(func(TestExtractor)      , False)
+        self.assertEqual(func(TestExtractorParent), False)
+        self.assertEqual(func(TestExtractorAlt)   , True)
+
+        config.set((), "blacklist", ":test_subcategory")
+        func = tjob._build_extractor_filter()
+        self.assertEqual(func(TestExtractor)      , False)
+        self.assertEqual(func(TestExtractorParent), True)
+        self.assertEqual(func(TestExtractorAlt)   , False)
+
+        config.set((), "whitelist", "test_category:test_subcategory")
+        func = tjob._build_extractor_filter()
+        self.assertEqual(func(TestExtractor)      , True)
+        self.assertEqual(func(TestExtractorParent), False)
+        self.assertEqual(func(TestExtractorAlt)   , False)
+
+
 class TestKeywordJob(TestJob):
     jobclass = job.KeywordJob
 
@@ -334,5 +359,10 @@ class TestExtractorException(Extractor):
         return 1/0
 
 
+class TestExtractorAlt(Extractor):
+    category = "test_category_alt"
+    subcategory = "test_subcategory"
+
+
 if __name__ == '__main__':
     unittest.main()