PGF service & minibar: only show dependency diagrams if the labels are known

+ The PGF service now reads and caches dependency label configuration files.
+ The grammar info returned by command=grammar has a new boolean field 
  'hasDependencyLabels' to indicate if dependency labels were found for
  the grammar. Also, command=deptree will now fail if no labels are present.
+ The minibar only shows word dependency trees if labels are present.
+ Also changed the type of getDepLabels from [String] -> Labels to
  String -> Labels, since all uses were in the form "getDepLabels . lines".

src/runtime/haskell/PGF/VisualizeTree.hs

@@ -16,7 +16,7 @@ module PGF.VisualizeTree
              , graphvizParseTree
              , graphvizParseTreeDep
              , graphvizDependencyTree
-             , getDepLabels
+             , Labels, getDepLabels
              , graphvizBracketedString
              , graphvizAlignment
              , gizaAlignment
@@ -232,8 +232,8 @@ graphvizDependencyTree format debug mlab ms pgf lang t =
 
 -- | Prepare lines obtained from a configuration file for labels for
 -- use with 'graphvizDependencyTree'. Format per line /fun/ /label/@*@.
-getDepLabels :: [String] -> Labels
-getDepLabels ss = Map.fromList [(mkCId f,ls) | f:ls <- map words ss]
+getDepLabels :: String -> Labels
+getDepLabels s = Map.fromList [(mkCId f,ls) | f:ls <- map words (lines s)]
 
 -- the old function, without dependencies
 graphvizParseTree :: PGF -> Language -> GraphvizOptions -> Tree -> String