Bundle all external dependencies and run more tests.

* .gitignore: Ignore texinfo files.

* .travis.yml (script): Make "check-fancy" to check contribs, not
just core.

* Makefile (ensure_ert,ensure_cl_lib): Remove targets since these
are bundled.
(compile): Don't download cl-lib.
(check): Don't download ert.
(clean): Look for .elc files everywhere.

* lib/hyperspec.el: Moved from top-level dir.
* lib/ert.el: New file.
* lib/ert-x.el: New file.
* lib/cllib.el: New file.

* slime-tests.el (traditional-recipe): New test, respect
tradition.
(require 'ert): Fallback to version bundled under lib/.
(slime-test-recipe-connect-forms): New var refactored from
previous tests.
(slime-test-recipe-check-repl): New function refactored from
previous tests.
(readme-recipe): Refactored.

* slime.el
(require 'cl-lib): fallback to version bundled under lib/.
(require 'hyperspec): look for version bundled under lib/.

* contrib/slime-parse.el (form-up-to-point.1): Skip for now, then analyse.

* contrib/slime-repl.el (move-around-and-be-nasty): Skip it. Causes other
tests to become unstable.
(interrupt-in-blocking-read): Skip for now, the analyse.

* doc/slime.texi (Installation): Remove subsection "Emacs 23
gotchas".
(Loading Contribs): Clarify function name to call for attempting
unload and give example.