Initial commit of ICL - Interactive Common Lisp

An enhanced REPL for Common Lisp with:
- Multi-line input and readline-style editing
- Persistent command history
- Tab completion for symbols and packages
- Extensible comma-prefixed command system
- Support for multiple Lisp implementations via Slynk
- Documentation lookup, object inspection, and tracing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>