MewBot adding lang to column templates

If you're going to use {{l}} in {{der3}}, you might as well wrap it in {{der-top3}} instead now that it's autobalancing.

I no longer use {{l}} in {{der3}}, but others do, and I'm not sure if there's a policy about what sorts of annotations should be added to items in a list of derived terms (i.e., whether I should be removing the annotations that someone else has added).