PGFService.hs: fix type error caused by change to PGF.graphvizParseTree

Note that some of the graphviz functions have backwards incompatible changes
that might also affect other clients of the PGF run-time library.

Also added graphvizDefaults and export it together with GraphvizOptions from 
the PGF run-time library.

src/runtime/haskell/PGF.hs

@@ -122,6 +122,8 @@ module PGF(
            graphvizBracketedString,
            graphvizAlignment,
            gizaAlignment,
+           GraphvizOptions(..),
+           graphvizDefaults,
  
            -- * Probabilities
            Probabilities,

src/runtime/haskell/PGF/VisualizeTree.hs

@@ -17,6 +17,7 @@
 
 module PGF.VisualizeTree 
              ( GraphvizOptions(..)
+             , graphvizDefaults
              , graphvizAbstractTree
              , graphvizParseTree
              , graphvizParseTreeOld
@@ -58,6 +59,8 @@ data GraphvizOptions = GraphvizOptions {noLeaves :: Bool,
                                         leafEdgeStyle :: String
                                        }
 
+graphvizDefaults = GraphvizOptions False False False "" "" "" "" "" ""
+
 
 -- | Renders abstract syntax tree in Graphviz format
 graphvizAbstractTree :: PGF -> (Bool,Bool) -> Tree -> String

src/server/PGFService.hs

@@ -338,7 +338,7 @@ outputGraphviz code =
         _     -> "application/binary"
 
 abstrTree pgf tree      = PGF.graphvizAbstractTree pgf (True,True) tree
-parseTree pgf lang tree = PGF.graphvizParseTree pgf lang tree
+parseTree pgf lang tree = PGF.graphvizParseTree pgf lang PGF.graphvizDefaults tree
 alignment pgf tree      = PGF.graphvizAlignment pgf (PGF.languages pgf) tree
 
 pipeIt2graphviz :: String -> String -> IO BS.ByteString