Silence makeinfo error during `make slime.info'

The error reported was:

  slime.texi:536: @itemx must follow @item
Use correct file name (README.md) in mkdist.sh.
Include contrib/ in distrubution built by mkdist.sh.
Highlight README.md's code snippet as Emacs Lisp.
Some slime asdf cleanups:
* Drop the unsupported :force hack from swank.asd
* Update some comments and docstrings
* Remove an obsolete #+asdf2
Send Travis email notifications to slime-cvs
Minor highlighting fix in README.md
Merge pull request #70 from nbtrap/include-contrib-in-mkdist

Include contrib/ in distribution built by mkdist.sh
Merge pull request #69 from nbtrap/fix-info-build

Silence makeinfo error during `make slime.info'
Merge remote-tracking branch 'origin/pr/68'

Conflicts:
	mkdist.sh
Replace .cvsignore with .gitignore
REPL prompt now resists being undone..

* contrib/Changelog: Use utf-8 coding.

* contrib/slime-repl.el (slime-repl-insert-prompt): Reset
`buffer-undo-list' after inserting a new prompt.
Fix mkdist.sh line endings

Closes issue #77
Merge pull request #76

Some ASDF cleanups.
Closes #78: `slime-edit-definition' on no symbol should prompt user.

* slime.el (slime-edit-definition): Fix bug introduced by changes
of 2013-12-30. Closes #78.
Disable email notifications from travis

We don't have a good place where to send them.
Use the correct ERT for Emacs 24

Make sure downloaded libraries are removed before testing with
Emacs 24, in particular the *.elc files.
Temporarily disable flow-control test

Because it randomly causes all tests to fail.
Fix and enhancements to slime-trace-dialog contrib.

* contrib/slime-trace-dialog.el
(slime-trace-dialog): Change advertised protocol, doesn't fetch
traces automatically, just specs and progress.
(slime-trace-dialog-fetch-specs): New interactive function.
(slime-trace-dialog-fetch-progress): New interactive function.
(slime-trace-dialog-fetch-status): Fetch local control, specs and
progress.
(slime-trace-dialog--clear-local-tree): Simplified.
(slime-trace-dialog--update-progress): "[refresh]" button degates
to `slime-trace-dialog-fetch-progress'.	 "[clear]" button always
shows if there is something to clear. Simplified.
(slime-trace-dialog--on-new-results): Adapt to new
`slime-trace-dialog--update-progress'
(slime-trace-dialog--mode-map): Bind 'g' to
`slime-trace-dialog-fetch-status'.

* contrib/swank-trace-dialog.lisp (dialog-trace): Don't set RETLIST-OF to a
symbol here, backends are responsible for that.
[Fix #72] Convert HACKING to CONTRIBUTING.md