Lamb: A Lambda Calculus Engine

## Todo (pre-release): - Fix parser (call parentheses) - Good command parsing (`:help`, `:save`, `:load`, `:macros` as a bare minimum) - Python files: installable, package list, etc - $\alpha$-equivalence check - Don't expand macros until you absolutely have to - Versioning - Clean up runner & printing - Count reductions ## Todo: - live syntax check - Command and macro autocomplete - step-by-step reduction - Documentation in README - Maybe a better icon?