refactor the API for random generation again. Now PGF contains probabilities in the abstract syntax

src/runtime/haskell/PGF/Forest.hs

@@ -72,7 +72,7 @@ bracketedTokn f@(Forest abs cnc forest root) =
                                                  cat = case isLindefCId fun of
                                                          Just cat -> cat
                                                          Nothing  -> case Map.lookup fun (funs abs) of
-                                                                       Just (DTyp _ cat _,_,_) -> cat
+                                                                       Just (DTyp _ cat _,_,_,_) -> cat
                                                  largs  = map (render forest) args
                                                  ltable = mkLinTable cnc isTrusted [] funid largs
                                              in ((cat,fid),either (const []) id $ getAbsTrees f arg Nothing,ltable)