[deviantart] ensure consistent username capitalization (#455)

The 'username' field was capitalized in a very inconsistent manner:
Either all lowercase, or as given by the input URL, or with the
"original" capitalization, depending on the extractor used among
other things.

Now usernames use their original capitalization for all extractors.
('UserName' instead of 'username' or 'uSeRnAmE')

gallery_dl/extractor/deviantart.py

@@ -29,7 +29,7 @@
 class DeviantartExtractor(Extractor):
     """Base class for deviantart extractors using the OAuth API"""
     category = "deviantart"
-    directory_fmt = ("{category}", "{author[username]!l}")
+    directory_fmt = ("{category}", "{username}")
     filename_fmt = "{category}_{index}_{title}.{extension}"
     root = "https://www.deviantart.com"
 
@@ -62,6 +62,7 @@ def items(self):
             self.group = not profile
             if self.group:
                 self.subcategory = "group-" + self.subcategory
+                self.user = self.user.lower()
             else:
                 self.user = profile["user"]["username"]
 
@@ -398,7 +399,7 @@ def deviations(self):
 class DeviantartFolderExtractor(DeviantartExtractor):
     """Extractor for deviations inside an artist's gallery folder"""
     subcategory = "folder"
-    directory_fmt = ("{category}", "{folder[owner]}", "{folder[title]}")
+    directory_fmt = ("{category}", "{username}", "{folder[title]}")
     archive_fmt = "F_{folder[uuid]}_{index}.{extension}"
     pattern = BASE_PATTERN + r"/gallery/(\d+)/([^/?&#]+)"
     test = (
@@ -418,14 +419,19 @@ class DeviantartFolderExtractor(DeviantartExtractor):
 
     def __init__(self, match):
         DeviantartExtractor.__init__(self, match)
-        self.fname = match.group(4)
-        self.folder = {"owner": self.user, "index": match.group(3)}
+        self.folder = None
+        self.folder_id = match.group(3)
+        self.folder_name = match.group(4)
 
     def deviations(self):
         folders = self.api.gallery_folders(self.user)
-        folder = self._find_folder(folders, self.fname)
-        self.folder["title"] = folder["name"]
-        self.folder["uuid"] = folder["folderid"]
+        folder = self._find_folder(folders, self.folder_name)
+        self.folder = {
+            "title": folder["name"],
+            "uuid" : folder["folderid"],
+            "index": self.folder_id,
+            "owner": self.user,
+        }
         return self.api.gallery(self.user, folder["folderid"], self.offset)
 
     def prepare(self, deviation):
@@ -472,6 +478,7 @@ def deviations(self):
 
         if deviation_id:
             deviation = self.api.deviation(deviation_id)
+            deviation["username"] = deviation["author"]["username"]
             pos = page.find("dev-page-download", pos)
             if pos >= 0:
                 deviation["_download"] = {
@@ -530,8 +537,8 @@ def deviations(self):
 class DeviantartCollectionExtractor(DeviantartExtractor):
     """Extractor for a single favorite collection"""
     subcategory = "collection"
-    directory_fmt = ("{category}", "{collection[owner]}",
-                     "Favourites", "{collection[title]}")
+    directory_fmt = ("{category}", "{username}", "Favourites",
+                     "{collection[title]}")
     archive_fmt = "C_{collection[uuid]}_{index}.{extension}"
     pattern = BASE_PATTERN + r"/favourites/(\d+)/([^/?&#]+)"
     test = (
@@ -546,14 +553,19 @@ class DeviantartCollectionExtractor(DeviantartExtractor):
 
     def __init__(self, match):
         DeviantartExtractor.__init__(self, match)
-        _, _, cid, self.cname = match.groups()
-        self.collection = {"owner": self.user, "index": cid}
+        self.collection = None
+        self.collection_id = match.group(3)
+        self.collection_name = match.group(4)
 
     def deviations(self):
         folders = self.api.collections_folders(self.user)
-        folder = self._find_folder(folders, self.cname)
-        self.collection["title"] = folder["name"]
-        self.collection["uuid"] = folder["folderid"]
+        folder = self._find_folder(folders, self.collection_name)
+        self.collection = {
+            "title": folder["name"],
+            "uuid" : folder["folderid"],
+            "index": self.collection_id,
+            "owner": self.user,
+        }
         return self.api.collections(self.user, folder["folderid"], self.offset)
 
     def prepare(self, deviation):
@@ -668,7 +680,7 @@ def _extract(self, data):
 
         # prepare deviation metadata
         deviation["description"] = extended.get("description", "")
-        deviation["username"] = self.user.lower()
+        deviation["username"] = deviation["author"]["username"]
         deviation["stats"] = extended["stats"]
         deviation["stats"]["comments"] = data["comments"]["total"]
         deviation["index"] = deviation["deviationId"]