* sly.el (sly-init-using-asdf): Use `format' not `pp-to-string'. Some
  lisps have trouble with newlines, like Allegro CL.
More sly-mrepl fixes

* contrib/sly-mrepl.el (sly-mrepl--ensure-newline): Must bind inhibit-read-only.
(sly-mrepl--freeze-prompt, sly-mrepl--unfreeze-prompt): Slightly safer.
(sly-mrepl-runonce-hook): Fix typo.
(:write-result): Remove. SLIME compatibility long gone in sly-mrepl.el.
(sly-mrepl-return): Improve assertions.
(sly-mrepl--teardown): Simpler teardown.

* contrib/swank-mrepl.lisp (mrepl-eval): Only set history if some values were resturned.
* sly.el (sly-define-channel-method): slightly better edebug spec.