Update nitrokey crate to 0.4.0

This change finally updates the version of the nitrokey crate that we
consume to 0.4.0. Along with that we update rand_core, one of its
dependencies, to 0.5.1. Further more we add cfg-if in version 0.1.10 and
getrandom in version 0.1.13, both of which are now new (non-development)
dependencies.

Import subrepo nitrokey/:nitrokey at e81057037e9b4f370b64c0a030a725bc6bdfb870
Import subrepo cfg-if/:cfg-if at 4484a6faf816ff8058088ad857b0c6bb2f4b02b2
Import subrepo getrandom/:getrandom at d661aa7e1b8cc80b47dabe3d2135b3b47d2858af
Import subrepo rand/:rand at d877ed528248b52d947e0484364a4e1ae59ca502

1 files changed, 47 insertions, 0 deletions

diff --git a/cfg-if/README.md b/cfg-if/README.md
new file mode 100644
index 0000000..50b5e3b
--- /dev/null
+++ b/cfg-if/README.md
@@ -0,0 +1,47 @@
+# cfg-if
+
+[Documentation](https://docs.rs/cfg-if)
+
+A macro to ergonomically define an item depending on a large number of #[cfg]
+parameters. Structured like an if-else chain, the first matching branch is the
+item that gets emitted.
+
+```toml
+[dependencies]
+cfg-if = "0.1"
+```
+
+## Example
+
+```rust
+cfg_if::cfg_if! {
+    if #[cfg(unix)] {
+        fn foo() { /* unix specific functionality */ }
+    } else if #[cfg(target_pointer_width = "32")] {
+        fn foo() { /* non-unix, 32-bit functionality */ }
+    } else {
+        fn foo() { /* fallback implementation */ }
+    }
+}
+
+fn main() {
+    foo();
+}
+```
+
+# License
+
+This project is licensed under either of
+
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+   http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in `cfg-if` by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.