[don't clear rules when adding new ones to an existing id with rules
John Meacham <john@repetae.net>**20060316003302] hunk ./Main.hs 152
-idann rs ps i nfo = return (props ps i nfo `mappend` rules rs i) where
+idann rs ps i nfo = return (rules rs i (props ps i nfo)) where
hunk ./Main.hs 158
-    rules rs i = Info.maybeInsert (getARules rs i) Info.empty
+    rules rs i = case getARules rs i of
+        Nothing -> id
+        Just x -> \nfo -> Info.insert (x `mappend` Info.fetch nfo) nfo