token: maintain of source, which retains original position information;
removed count/counted, advance position via scanned source;
;;;
;;; $Id$
;;;
;;; Options for Proof General
;; Examples for sensible settings:
;(custom-set-variables '(isar-eta-contract nil))
;(custom-set-faces
; '(proof-locked-face
; ((((type x) (class color) (background light)) (:background "lightsteelblue2")))))