writerfilter: drop no longer needed TBD class in doctok

Change-Id: If5ff0aef278f307229c4081f7bc740fb025c3392
writerfilter: drop no longer needed LineProps class in doctok

Change-Id: I3b6c7b233d30ee0ec0d57b6869117ab7616d0868
writerfilter: drop no longer needed Fib class in doctok

Change-Id: I1035148686026f0c0c27bad70c0c2e5d0f62b915
writerfilter: drop no longer needed BKF class in doctok

Change-Id: Id09b74e8d29d97da2dedcb7a906748193c5a77aa