Vendor things

third-party/vendor/num-bigint/README.md

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+# num-bigint
+
+[![crate](https://img.shields.io/crates/v/num-bigint.svg)](https://crates.io/crates/num-bigint)
+[![documentation](https://docs.rs/num-bigint/badge.svg)](https://docs.rs/num-bigint)
+[![minimum rustc 1.31](https://img.shields.io/badge/rustc-1.31+-red.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
+[![build status](https://github.com/rust-num/num-bigint/workflows/master/badge.svg)](https://github.com/rust-num/num-bigint/actions)
+
+Big integer types for Rust, `BigInt` and `BigUint`.
+
+## Usage
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+num-bigint = "0.4"
+```
+
+## Features
+
+The `std` crate feature is enabled by default, and is mandatory before Rust
+1.36 and the stabilized `alloc` crate.  If you depend on `num-bigint` with
+`default-features = false`, you must manually enable the `std` feature yourself
+if your compiler is not new enough.
+
+### Random Generation
+
+`num-bigint` supports the generation of random big integers when the `rand`
+feature is enabled. To enable it include rand as
+
+```toml
+rand = "0.8"
+num-bigint = { version = "0.4", features = ["rand"] }
+```
+
+Note that you must use the version of `rand` that `num-bigint` is compatible
+with: `0.8`.
+
+## Releases
+
+Release notes are available in [RELEASES.md](RELEASES.md).
+
+## Compatibility
+
+The `num-bigint` crate is tested for rustc 1.31 and greater.
+
+## Alternatives
+
+While `num-bigint` strives for good performance in pure Rust code, other
+crates may offer better performance with different trade-offs.  The following
+table offers a brief comparison to a few alternatives.
+
+| Crate             | License        | Min rustc | Implementation | Features |
+| :---------------  | :------------- | :-------- | :------------- | :------- |
+| **`num-bigint`**  | MIT/Apache-2.0 | 1.31      | pure rust | dynamic width, number theoretical functions |
+| [`awint`]         | MIT/Apache-2.0 | 1.66      | pure rust | fixed width, heap or stack, concatenation macros |
+| [`bnum`]          | MIT/Apache-2.0 | 1.61      | pure rust | fixed width, parity with Rust primitives including floats |
+| [`crypto-bigint`] | MIT/Apache-2.0 | 1.57      | pure rust | fixed width, stack only |
+| [`ibig`]          | MIT/Apache-2.0 | 1.49      | pure rust | dynamic width, number theoretical functions |
+| [`rug`]           | LGPL-3.0+      | 1.65      | bundles [GMP] via [`gmp-mpfr-sys`] | all the features of GMP, MPFR, and MPC |
+
+[`awint`]: https://crates.io/crates/awint
+[`bnum`]: https://crates.io/crates/bnum
+[`crypto-bigint`]: https://crates.io/crates/crypto-bigint
+[`ibig`]: https://crates.io/crates/ibig
+[`rug`]: https://crates.io/crates/rug
+
+[GMP]: https://gmplib.org/
+[`gmp-mpfr-sys`]: https://crates.io/crates/gmp-mpfr-sys
+
+## License
+
+Licensed under either of
+
+ * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
+ * [MIT license](http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.