* README.md (Fork): Explain the "why of SLY"
Fix gray stream issue for SBCL

The pretty printer seems to call the non-standard
stream-line-length generic function.

* lib/lisp/backend/swank-sbcl.lisp (sb-gray:stream-line-length):
  Implement default.

(cherry picked from SLIME commit
b3bd68064b2012eca6b61cc938288f6c245acbe9)

Conflicts:
	ChangeLog
Minor cleanup in slime-parse-tests.el

* test/slime-parse-tests.el (form-up-to-point.1): Don't
hardcode swank::%cursor-marker% use the slime-cursor-marker
constant instead.

(cherry picked from SLIME commit
228285b8bee3289c28e6a8b086174d7ce1be5cfd)

Conflicts:
	contrib/ChangeLog
	contrib/test/sly-parse-tests.el
Massive swank -> slynk rename
Massive sldb -> sly-db rename
Add sly-retro contrib and enable it by default

This contrib ensures that SLY is not locked out of the existing SWANK
communication protocol.

* sly-autoloads.el (sly-contribs): Add `sly-retro' contrib by default.

* sly.el (sly-contribs): Add `sly-retro' contrib by default.
(sly-net-send-translator): New variable.
(sly-net-send): Use it.

* slynk.asd (:slynk-retro): New defsystem.

* contrib/sly-retro.el: New contrib.

* contrib/slynk-retro.lisp (:slynk-retro): New package.

* lib/lisp/slynk-rpc.lisp (*translating-swank-to-slynk*): New variable.
(*validate-input*): Removed.
(read-form): Use *TRANSLATING-SWANK-TO-SLYNK* and TRANSLATING-READ.
(validating-read): Removed.
(simple-read): Removed.
(translating-read): New.
(maybe-convert-package-designator): New.

* lib/lisp/slynk.lisp (*slynk-require-hook*): New hook.
(slynk-require): Run *SLYNK-REQUIRE-HOOK*
(cherry picked from commit 23548d20eefe885c16618d27145cc23bc8eef8b9)
NEWS.md tweaks
Update CONTRIBUTING.md with SLYNK/SWANK description.