start a tshell in vl toolkit

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2523 303c5b2c-9740-0410-b014-fd8f9db7be32
Quicklisp: minor tweaks to simplify the build

VL: start cleaning up parser code, switch to defines for parse-expressions
    and parse-statements

STD: tweak std package to include acl2::defines, and add it to *std-exports*

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2526 303c5b2c-9740-0410-b014-fd8f9db7be32
Updated documentation for imminent acl2-devel fix -- quoting :doc
note-6-5:

  We have made several system functions untouchable (see
  [remove-untouchable]), in order to prevent soundness bugs. We thank
  Jared Davis and Sol Swords for sending us an example that used a
  call of one of these functions to prove nil. We have placed that
  example into a comment in Community Books file
  system/doc/acl2-doc.lisp, form ([defxdoc] note-6-5 ...).


git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2527 303c5b2c-9740-0410-b014-fd8f9db7be32