Incorporated mod from J (with further mods to some books) for untranslating car-cdr nests.

Quoting :doc note-7-0:

  Nests of [car] and [cdr] calls are now printed (``untranslated'')
  differently. The old method availed itself of all 28 of the car-cdr
  macros. The new method only introduces 6 of them: cadr, caddr,
  cadddr, cddr, cdddr, cddddr. This code never introduces such macros
  as caar or cddaar, preferring cars and cdrs when necessary. Lisp
  programmers tend to recognize cadr, caddr, and cadddr as the
  accessors for the 1st, 2nd, and 3rd (0-based) elements of a list.
  See community book books/system/untranslate-car-cdr.lisp for
  further discussion and a correctness proof.