The simple arglists version on the sly.el side was removed. The SWANK
interface stays, for backward/SLIME compatibility and for whoever
wants to use it.

* sly.el (sly-space, sly-echo-arglist-function, sly-echo-arglist)
(sly-show-arglist, sly-operator-before-point-function)
(sly-operator-before-point, sly-lisp-operator-before-point): Removed.

* contrib/sly-autodoc.el: set lexical-binding to t.
(sly-autodoc): Use just `sly-autodoc-mode'
(sly-use-autodoc-mode): Remove this defcustom.
(sly-autodoc--make-rpc-form, sly-autodoc--last-buffer-form)
(sly-autodoc--last-autodoc, sly-autodoc--format): Rename.
(sly-autodoc-mode): Use `define-minor-mode
(sly-autodoc-maybe-enable): Removed.
(eldoc-display-message-no-interference-p): `sly-bind-keys' call
was kinda gross.