provide type information for Queue messages

Child extractors are now directly constructed with Extractor.from_url()
if the extractor class is known beforehand, instead of using
extractor.find() and searching through all possible extractor classes.

gallery_dl/extractor/xvideos.py

@@ -99,7 +99,7 @@ class XvideosUserExtractor(XvideosExtractor):
     test = (
         ("https://www.xvideos.com/profiles/pervertedcouple", {
             "url": "a413f3e60d6d3a2de79bd44fa3b7a9c03db4336e",
-            "keyword": "a796760d34732adc7ec52a8feb057515209a2ca6",
+            "keyword": "ef941489354fd8f4754c8a87cffd5e2429a6387c",
         }),
         ("https://www.xvideos.com/profiles/niwehrwhernvh", {
             "exception": exception.NotFoundError,
@@ -123,9 +123,12 @@ class XvideosUserExtractor(XvideosExtractor):
             del data["galleries"]["0"]
 
         galleries = [
-            {"gallery_id": text.parse_int(gid),
-             "title": text.unescape(gdata["title"]),
-             "count": gdata["nb_pics"]}
+            {
+                "gallery_id": text.parse_int(gid),
+                "title": text.unescape(gdata["title"]),
+                "count": gdata["nb_pics"],
+                "_extractor": XvideosGalleryExtractor,
+            }
             for gid, gdata in data["galleries"].items()
         ]
         galleries.sort(key=lambda x: x["gallery_id"])