SLY is a fork of SLIME. We track its bugfixes, particularly to the
implementation backends. All SLIME's familiar features (debugger, inspector,
xref, etc...) are still available, with improved overall UX.

SLY's highlights are:
- A full-featured REPL based on Emacs's comint.el. Everything can be copied to
  the REPL.
- Stickers, or live code annotations that record values as code traverses them.
- Flex-style completion out-of-the-box, using Emacs's completion API. Company,
  Helm, and other supported natively, no plugin required.
- An interactive Trace Dialog.
- Cleanly ASDF-loaded by default, including contribs, enabled out-of-the-box.
- Multiple inspectors and multiple REPLs.
- "Presentations" replaced by interactive backreferences which highlight the
  object and remain stable throughout the REPL session.
- Support for NAMED-READTABLES, macrostep.el and quicklisp.
- A portable, annotation-based stepper in early but functional prototype stage.