Workaround until FeedHQ manages both "ot" and "n"

FeedHQ fetches too many items when one passes both "ot" and "n" parameters in our request : https://feedhq.org/reader/api/0/stream/contents/feed/[[ESCAPED_FEED_URL]]?client=ViennaRSS&comments=false&likes=false&ot=[[TIMESTAMP]]&n=500&ck=[[LAST_FETCH_TIMESTAMP]]

So, we limit ourselves to 100 ; but we might miss some articles this way…