Minor cleanup sly-y-or-n-p -> sly-remote-y-or-n-p

* sly.el (sly-remote-y-or-n-p): Rename from `sly-y-or-n-p'.
(sly-dispatch-event): Use it.
Fix https://github.com/slime/slime/issues/195

sb-sys:enable-interrupt does not exist on SBCL +win32
so disable it on Windows.

* slynk/backend/slynk-sbcl.lisp (add-sigio-handler,
remove-sigio-handlers): Disable it on Windows along with
install-sigint-handler.

(cherry picked from SLIME commit 0ed3782ee2ad9e84da4532408ca7ccdd0dc3e568)

Conflicts:
	ChangeLog
* slynk/backend/slynk-cmucl.lisp, slynk/backend/slynk-sbcl.lisp: Whitespace cleanup.

(cherry picked from SLIME commit a16c872010316177661e74729cda9982775e936a)

Conflicts:
	ChangeLog
	slynk/backend/slynk-cmucl.lisp
	slynk/backend/slynk-sbcl.lisp
* swank/cmucl.lisp: Require at least version 20c and remove some

code that was there only for compatibility with older versions.

(cherry picked from SLIME commit
d6e3d50902a062739b0f00f43d8780a2ba427a6d)

Conflicts:
	ChangeLog
	slynk/backend/slynk-cmucl.lisp
Can't use Gray streams for ABCL

* slynk/backend/slynk-abcl.lisp (make-output-stream,
make-input-stream): Use ext:make-slime-output-stream because ABCL's
Gray streams don't work well enough.
* slynk/slynk-loader.lisp (*sysdep-files*, *slynk-files*): Don't load
slynk/slynk-gray.lisp for ABCL.
* slynk/slynk.asd (*sysdep-files*, *slynk-files*): Don't load
slynk/slynk-gray.lisp for ABCL.

(cherry picked from SLIME commit
4d69a95faff31286954ccb107e98a09b7db23436)

Conflicts:
	ChangeLog
	slynk/slynk-loader.lisp