fix lexer/parser bugs, add code in file-thread.sml to handle loading/saving of files (but loading is not completely finished yet)

fcore/quad-tree.sml

@@ -381,23 +381,6 @@ struct
       else y
   end
 
-  fun printItem {x, y, ex, ey, data} =
-    let
-      val msg = String.concat
-        [ "{x = "
-        , Int.toString x
-        , ", y = "
-        , Int.toString y
-        , ", ex = "
-        , Int.toString ex
-        , ", ey = "
-        , Int.toString ey
-        , "}\n"
-        ]
-    in
-      print msg
-    end
-
   local
     fun loop (tree, grid) =
       case tree of