* emacs-lisp/ert.el (ert--explain-equal): New function.
(ert--explain-equal-rec): Renamed from `ert--explain-not-equal'.
All callers changed.
(ert--explain-equal-including-properties): Renamed from
`ert--explain-not-equal-including-properties'. All callers
changed.
* automated/ert-tests.el (ert-test-explain-not-equal-keymaps):
New test.
* Makefile.in, configure.in, doc/misc/Makefile.in, doc/misc/makefile.w32-in:
Add ERT. Make "make check" run tests in test/automated.
* doc/misc/ert.texi, lisp/emacs-lisp/ert.el, lisp/emacs-lisp/ert-x.el:
New files.
* test/automated: New directory.