[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 @@ BASE_PATTERN = (
 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 @@ class DeviantartExtractor(Extractor):
             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 @@ class DeviantartGalleryExtractor(DeviantartExtractor):
 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 @@ class DeviantartStashExtractor(DeviantartExtractor):
 
         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 @@ class DeviantartFavoriteExtractor(DeviantartExtractor):
 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 @@ class DeviantartExtractorV2(DeviantartExtractor):
 
         # 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"]