yield 3-tuples for Message.Directory

adapt tuples to the same length and semantics as other messages

gallery_dl/extractor/pixnet.py

@@ -83,7 +83,7 @@ class PixnetImageExtractor(PixnetExtractor):
         data["blog"] = self.blog
         data["user"] = data.pop("author_name")
 
-        yield Message.Directory, data
+        yield Message.Directory, "", data
         yield Message.Url, data["url"], data
 
 
@@ -100,7 +100,7 @@ class PixnetSetExtractor(PixnetExtractor):
         page = self.request(url, encoding="utf-8").text
         data = self.metadata(page)
 
-        yield Message.Directory, data
+        yield Message.Directory, "", data
         for num, info in enumerate(self._pagination(page), 1):
             url, pos = text.extract(info, ' href="', '"')
             src, pos = text.extract(info, ' src="', '"', pos)