Removed support for the nu-rewriter.  Fixed watch-raw.lsp as per suggestions from Bob Boyer.  Minor updates to installation instructions, :doc memoize, home page, and default-state-vars, for ACL2(h) conversion.

Quoting :doc note-7-0:

  The nu-rewriter contained special provisions for rewriting
  expressions composed of [nth], [update-nth], and
  [update-nth-array], together with [let] expressions and other
  applications of non-recursive functions or [lambda] expressions. An
  email query was sent to the acl2 mailing list on 10/24/2014, giving
  people an opportunity to object to the removal of this feature.
  Nobody objected, so we have removed it in order to simplify the
  ACL2 code base. Thanks to David Rager for suggesting this sort of
  code clean-up. Note that some system functions, for example
  all-equal, have been deleted in support of this change.

Quoting :doc note-7-0-books:

  The watch utility works again. Thanks to Bob Boyer for providing
  fixes. To use this utility:

    (include-book "centaur/memoize/old/watch" :dir :system :ttags :all)
    :q
    (watch)
    (lp)
    ; Now in Emacs, bring into a buffer the file reported by (watch), whose
    ; name is of the form watch-output-temp-n.lsp.  Then execute ACL2 forms.