Vendor dependencies for 0.3.0 release

vendor/rand_distr/README.md

@@ -0,0 +1,57 @@
+# rand_distr
+
+[![Test Status](https://github.com/rust-random/rand/workflows/Tests/badge.svg?event=push)](https://github.com/rust-random/rand/actions)
+[![Latest version](https://img.shields.io/crates/v/rand_distr.svg)](https://crates.io/crates/rand_distr)
+[![Book](https://img.shields.io/badge/book-master-yellow.svg)](https://rust-random.github.io/book/)
+[![API](https://img.shields.io/badge/api-master-yellow.svg)](https://rust-random.github.io/rand/rand_distr)
+[![API](https://docs.rs/rand_distr/badge.svg)](https://docs.rs/rand_distr)
+[![Minimum rustc version](https://img.shields.io/badge/rustc-1.36+-lightgray.svg)](https://github.com/rust-random/rand#rust-version-requirements)
+
+Implements a full suite of random number distribution sampling routines.
+
+This crate is a superset of the [rand::distributions] module, including support
+for sampling from Beta, Binomial, Cauchy, ChiSquared, Dirichlet, Exponential,
+FisherF, Gamma, Geometric, Hypergeometric, InverseGaussian, LogNormal, Normal,
+Pareto, PERT, Poisson, StudentT, Triangular and Weibull distributions.  Sampling
+from the unit ball, unit circle, unit disc and unit sphere surfaces is also
+supported.
+
+It is worth mentioning the [statrs] crate which provides similar functionality
+along with various support functions, including PDF and CDF computation. In
+contrast, this `rand_distr` crate focuses on sampling from distributions.
+
+## Portability and libm
+
+The floating point functions from `num_traits` and `libm` are used to support
+`no_std` environments and ensure reproducibility. If the floating point
+functions from `std` are preferred, which may provide better accuracy and
+performance but may produce different random values, the `std_math` feature
+can be enabled.
+
+## Crate features
+
+-   `std` (enabled by default): `rand_distr` implements the `Error` trait for
+    its error types. Implies `alloc` and `rand/std`.
+-   `alloc` (enabled by default): required for some distributions when not using
+    `std` (in particular, `Dirichlet` and `WeightedAliasIndex`).
+-   `std_math`: see above on portability and libm
+-   `serde1`: implement (de)seriaialization using `serde`
+
+## Links
+
+-   [API documentation (master)](https://rust-random.github.io/rand/rand_distr)
+-   [API documentation (docs.rs)](https://docs.rs/rand_distr)
+-   [Changelog](CHANGELOG.md)
+-   [The Rand project](https://github.com/rust-random/rand)
+
+
+[statrs]: https://github.com/boxtown/statrs
+[rand::distributions]: https://rust-random.github.io/rand/rand/distributions/index.html
+
+## License
+
+`rand_distr` is distributed under the terms of both the MIT license and the
+Apache License (Version 2.0).
+
+See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT), and
+[COPYRIGHT](COPYRIGHT) for details.