"on" -> "at"

docs/Changelog

@@ -3,6 +3,7 @@ pisg (0.68) - ??
      + ColorScheme 'none' will generate the color gradient again, the gradient
        is dropped with HiCell="".
      + More smileys (SF #1264834).
+     + Fix English preposition (thanks, Barry Suridge).
    Torbjörn:
      + Generate stats in multiple languages in a single run.
 

lang.txt

@@ -152,7 +152,7 @@ urlstopic = "Most referenced URLs"
 chartstopic = "[:channel] Music Charts"
 notopic = "A topic was never set on this channel."
 mostnickstopic = "Users with most nicknames"
-bylinetopic = "[:date] on [:time] by [:nick]"
+bylinetopic = "[:date] at [:time] by [:nick]"
 dailyactivitytopic = "Daily activity (last [:n] days)"
 activegenderstopic = "Most active gender"