Introduce EOT (end-of-transmission) marker

Change-Id: I7946e95c80fd7cd6ac1e0dd2fe5b188105f30534
diff --git a/token_writer_test.go b/token_writer_test.go
index 9678157..84a4074 100644
--- a/token_writer_test.go
+++ b/token_writer_test.go
@@ -21,9 +21,11 @@
 
 	tws.Token(0, []rune{'d', 'e', 'f'})
 
-	tws.SentenceEnd()
+	tws.SentenceEnd(0)
+
+	tws.TextEnd(0)
 
 	tws.Flush()
 
-	assert.Equal("abc\ndef\n\n", w.String())
+	assert.Equal("abc\ndef\n\n\n", w.String())
 }