[common] simplify 'user' extractors by using 'Dispatch' mixin

gallery_dl/extractor/deviantart.py

@@ -8,7 +8,7 @@
 
 """Extractors for https://www.deviantart.com/"""
 
-from .common import Extractor, Message
+from .common import Extractor, Message, Dispatch
 from .. import text, util, exception
 from ..cache import cache, memcache
 import collections
@@ -873,17 +873,11 @@ x2="45.4107524%" y2="71.4898596%" id="app-root-3">\
                    .replace("\\\\", "\\")
 
 
-class DeviantartUserExtractor(DeviantartExtractor):
+class DeviantartUserExtractor(Dispatch, DeviantartExtractor):
     """Extractor for an artist's user profile"""
-    subcategory = "user"
     pattern = BASE_PATTERN + r"/?$"
     example = "https://www.deviantart.com/USER"
 
-    def initialize(self):
-        pass
-
-    skip = Extractor.skip
-
     def items(self):
         base = "{}/{}/".format(self.root, self.user)
         return self._dispatch_extractors((