[reddit] add 'limit' option (#7997 #8012 #8092)

change default value from 100 to null,
i.e. don't send a 'limit' parameter

gallery_dl/extractor/reddit.py

@@ -426,13 +426,11 @@ class RedditAPI():
     def submissions_subreddit(self, subreddit, params):
         """Collect all (submission, comments)-tuples of a subreddit"""
         endpoint = subreddit + "/.json"
-        params["limit"] = 100
         return self._pagination(endpoint, params)
 
     def submissions_user(self, user, params):
         """Collect all (submission, comments)-tuples posted by a user"""
         endpoint = "/user/" + user + "/.json"
-        params["limit"] = 100
         return self._pagination(endpoint, params)
 
     def morechildren(self, link_id, children):
@@ -532,6 +530,9 @@ class RedditAPI():
             id_max = float("inf")
         date_min, date_max = self.extractor._get_date_min_max(0, 253402210800)
 
+        if limit := self.extractor.config("limit"):
+            params["limit"] = limit
+
         while True:
             data = self._call(endpoint, params)["data"]