plan9 rc in rust

• Goal: Implement plan9 rc in Rust.
• Plan: Stay true to 9front implementation.
• License: GPL-3.0-or-later
• Disclaimer: This is just a hobby project. Don't expect anything anytime soon.

ChangeLog

0.0.1-alpha.1

• add initial repl using rustyline.
• implement initial lexer/tokenizer using nom.