Integrate some fixes from Fare

* sbcl-pprint-patch.lisp: Handle package-unlocking and error
  clobbering in patch file itself, not its users.

* swank-sbcl.lisp (swank-backend::sbcl-wrap): Remove a warning.

* swank.asd: Cleanup some comments.

* contrib/swank-presentation-streams.lisp [sbcl]: Simplify loading of
  sbcl-pprint-patch when using swank-loader.lisp.
Make it work for SBCL (and fix ChangeLog files)

* swank.asd (:swank): swank-gray.lisp must be loaded for sbcl too.