Fixed an error message for ill-formed :expand hints to mention that :lambdas
is legal.

Improved the error message when attempting to apply trace$ to a macro.

Quoting :doc note-6-5:

  The [walkabout] utility could cause hard Lisp errors when the current
  package is other than "ACL2". This has been fixed. Thanks to Sol
  Swords for bringing this bug to our attention and suggesting a fix.


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1303 5d84a466-a78b-0930-a311-59b22171a541