* Nix flakes and direnv for localdev and CI

* New, simpler CI

* Many more lints enabled and fixed

    * Fixed unicode usage in `input_line` view

    * Documented all public and private items

    * Added `#[must_use]` annotations where reasonable

* Remove pre-commit hooks since it's much easier to run CI locally now

* Added markdownlint and fixed its suggestions

* Added shellcheck and shfmt

* Update my email address

* Update links to the new domain

* Rust 2021 edition

* CommonMark'd licenses