Vendor dependencies

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vendor/assert_matches/README.md

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+# assert_matches
+
+Provides a macro, `assert_matches`, which tests whether a value
+matches a given pattern, causing a panic if the match fails.
+
+[Documentation](https://docs.rs/assert_matches/)
+
+```rust
+#[macro_use] extern crate assert_matches;
+
+#[derive(Debug)]
+enum Foo {
+    A(i32),
+    B(i32),
+}
+
+let a = Foo::A(1);
+
+assert_matches!(a, Foo::A(_));
+
+assert_matches!(a, Foo::A(i) if i > 0);
+```
+
+To include in your project, only when tests are compiled, add the following
+to your Cargo.toml:
+
+```toml
+[dev-dependencies]
+assert_matches = "1.5"
+```
+
+And add the following to your crate root:
+
+```rust
+#[cfg(test)] #[macro_use]
+extern crate assert_matches;
+```
+
+## License
+
+`assert_matches` is distributed under the terms of both the MIT license and the
+Apache License (Version 2.0).
+
+See LICENSE-APACHE and LICENSE-MIT for details.