feat(quickjs): add quickjs

from: https://crates.io/crates/quick-js

quickjs/external/quickjs-rs/README.md

@@ -0,0 +1,91 @@
+# quickjs-rs
+
+[![Crates.io](https://img.shields.io/crates/v/quick-js.svg?maxAge=3600)](https://crates.io/crates/quick-js)
+[![docs.rs](https://docs.rs/quick-js/badge.svg)](https://docs.rs/quick-js)
+[![Build Status](https://github.com/theduke/quickjs-rs/workflows/CI/badge.svg)
+
+A Rust wrapper for [QuickJS](https://bellard.org/quickjs/). 
+
+QuickJS is a new, small Javascript engine by Fabrice Bellard and Charlie Gordon. 
+It is fast and supports the full ES2020 specification.
+
+This crate allows you to easily run and integrate with Javascript code from Rust.
+
+## Quickstart
+
+```toml
+[dependencies]
+quick-js = "0.3.3"
+```
+
+```rust
+use quick_js::{Context, JsValue};
+
+let context = Context::new().unwrap();
+
+// Eval.
+
+let value = context.eval("1 + 2").unwrap();
+assert_eq!(value, JsValue::Int(3));
+
+let value = context.eval_as::<String>(" var x = 100 + 250; x.toString() ").unwrap();
+assert_eq!(&value, "350");
+
+// Callbacks.
+
+context.add_callback("myCallback", |a: i32, b: i32| a + b).unwrap();
+
+context.eval(r#"
+    // x will equal 30
+    var x = myCallback(10, 20);
+"#).unwrap();
+```
+
+## Optional Features
+
+The crate supports the following features:
+
+* `chrono`: chrono integration
+    - adds a `JsValue::Date` variant that can be (de)serialized to/from a JS `Date`
+* `bigint`: arbitrary precision integer support via [num-bigint](https://github.com/rust-num/num-bigint)
+* `log`: allows forwarding `console.log` messages to the `log` crate.
+    Note: must be enabled with `ContextBuilder::console(quick_js::console::LogConsole);`
+
+* `patched` 
+    Enabled automatically for some other features, like `bigint`. 
+    You should not need to enable this manually.
+    Applies QuickJS patches that can be found in `libquickjs-sys/embed/patches` directory.
+
+
+## Installation
+
+By default, quickjs is **bundled** with the `libquickjs-sys` crate and
+automatically compiled, assuming you have the appropriate dependencies.
+
+### Windows Support
+
+Windows is only supported with the [MSYS2](https://www.msys2.org/) environment 
+and `x86_64-pc-windows-gnu` target architecture. 
+
+If you have MSYS2 installed and the MSYS `bin` directory in your path, you can
+compile quickjs with `cargo build --target="x86_64-pc-windows-gnu"`. 
+
+The target can also be configured permanently via a 
+[cargo config file](https://doc.rust-lang.org/cargo/reference/config.html) or 
+the `CARGO_BUILD_TARGET` env var.
+
+### System installation
+
+To use the system installation, without the bundled feature, first install the required 
+dependencies, and then compile and install quickjs.
+
+```bash
+# Debian/Ubuntu: apt-get install -y curl xz-utils build-essential gcc-multilib libclang-dev clang
+mkdir quickjs 
+curl -L https://bellard.org/quickjs/quickjs-2019-07-09.tar.xz | tar xJv -C quickjs --strip-components 1
+cd quickjs
+sudo make install
+```
+
+You then need to disable the `bundled` feature in the `libquickjs-sys` crate to
+force using the system version.