Jon Oddie authored Oct 22, 2015 and Luís Oliveira committed Feb 02, 2016

Provide slightly fancier in-place macroexpansion by integrating with the
`macrostep.el' library originally written for Emacs Lisp.  This commit
is a squashed version of work co-authored with Luís Oliveira
<luismbo@gmail.com>.

* lib/macrostep.el: New file.  This is a bundled version of the library
developed at http://github.com/joddie/macrostep and also available via
MELPA.  The bundled copy will be used as a fallback if it is not
installed separately.

* contrib/slime-macrostep.el: New file.
* contrib/swank-macrostep.lisp: New file.
* contrib/test/slime-macrostep-tests.el: New file.
* contrib/slime-fancy.el (slime-fancy): Add `slime-macrostep'.

* swank/backend.lisp (call-with-macro-form-collector): New function.
(with-collected-macro-forms): Use it.  Also, optionally bind a
variable to the result of INSTRUMENTED-FORM.
(collect-macro-forms): Replace let+setq with the new
WITH-COLLECTED-MACRO-FORMS syntax.

* swank/sbcl.lisp (collect-macro-forms): SBCL implementation using a
  code-walker.
* swank/abcl.lisp (collect-macro-forms): ABCL implementation
  using WITH-COLLECTED-MACRO-FORMS.
* swank/clisp.lisp (collect-macro-forms): CLISP implementation using
  WITH-COLLECTED-MACRO-FORMS.

* swank-loader.lisp (*contribs*): Add `swank-macrostep'.