Support token offsets in token writer

Change-Id: I7db20d8f26fd87a2f43c3a6599bfeba050fc340a
diff --git a/datok.go b/datok.go
index f8fccaa..f804bf0 100644
--- a/datok.go
+++ b/datok.go
@@ -746,7 +746,7 @@
 
 // Transduce input to ouutput
 func (dat *DaTokenizer) Transduce(r io.Reader, w io.Writer) bool {
-	return dat.TransduceTokenWriter(r, NewTokenWriterSimple(w))
+	return dat.TransduceTokenWriter(r, NewTokenWriter(w))
 }
 
 // TransduceTokenWriter transduces an input string against
@@ -757,7 +757,7 @@
 // Based on Mizobuchi et al (2000), p. 129,
 // with additional support for IDENTITY, UNKNOWN
 // and EPSILON transitions and NONTOKEN and TOKENEND handling.
-func (dat *DaTokenizer) TransduceTokenWriter(r io.Reader, w TokenWriterI) bool {
+func (dat *DaTokenizer) TransduceTokenWriter(r io.Reader, w *TokenWriter) bool {
 	var a int
 	var t0 uint32
 	t := uint32(1) // Initial state