Add experimental `sly-profiler' contrib

* lib/lisp/slynk.lisp: Export TO-LINE

* contrib/sly-fancy.el (sly-fancy): Add experimental `sly-profiler'. Very broken still.

* contrib/sly-profiler.el: New file.

* contrib/slynk-profiler.lisp: New file.
* contrib/slynk-retro.lisp (:slynk-retro): Must provide itself.
* contrib/slynk-trace-dialog.lisp (instrument): And and export INSTRUMENT macro.