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, 24 insertions, 7 deletions

diff --git a/rand/rand_core/README.md b/rand/rand_core/README.md
index dee6504..467e66f 100644
--- a/rand/rand_core/README.md
+++ b/rand/rand_core/README.md
@@ -6,7 +6,7 @@
 [![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_core)
 [![API](https://docs.rs/rand_core/badge.svg)](https://docs.rs/rand_core)
-[![Minimum rustc version](https://img.shields.io/badge/rustc-1.22+-lightgray.svg)](https://github.com/rust-random/rand#rust-version-requirements)
+[![Minimum rustc version](https://img.shields.io/badge/rustc-1.32+-lightgray.svg)](https://github.com/rust-random/rand#rust-version-requirements)
 
 Core traits and error types of the [rand] library, plus tools for implementing
 RNGs.
@@ -25,7 +25,7 @@ Links:
 
 -   [API documentation (master)](https://rust-random.github.io/rand/rand_core)
 -   [API documentation (docs.rs)](https://docs.rs/rand_core)
--   [Changelog](CHANGELOG.md)
+-   [Changelog](https://github.com/rust-random/rand/blob/master/rand_core/CHANGELOG.md)
 
 [rand]: https://crates.io/crates/rand
 
@@ -40,17 +40,34 @@ The `rand_core` crate provides:
 
 The traits and error types are also available via `rand`.
 
+## Versions
+
+The current version is:
+```
+rand_core = "0.5.0"
+```
+
+Rand libs have inter-dependencies and make use of the
+[semver trick](https://github.com/dtolnay/semver-trick/) in order to make traits
+compatible across crate versions. (This is especially important for `RngCore`
+and `SeedableRng`.) A few crate releases are thus compatibility shims,
+depending on the *next* lib version (e.g. `rand_core` versions `0.2.2` and
+`0.3.1`). This means, for example, that `rand_core_0_4_0::SeedableRng` and
+`rand_core_0_3_0::SeedableRng` are distinct, incompatible traits, which can
+cause build errors. Usually, running `cargo update` is enough to fix any issues.
+
 ## Crate Features
 
 `rand_core` supports `no_std` and `alloc`-only configurations, as well as full
 `std` functionality. The differences between `no_std` and full `std` are small,
-comprising `RngCore` support for `Box<R>` types where `R: RngCore`, as well as
+comprising `RngCore` support for `Box<R>` types where `R: RngCore`,
+`std::io::Read` support for types supporting `RngCore`, and
 extensions to the `Error` type's functionality.
 
-Due to [rust-lang/cargo#1596](https://github.com/rust-lang/cargo/issues/1596),
-`rand_core` is built without `std` support by default. Since features are
-unioned across the whole dependency tree, any crate using `rand` with its
-default features will also enable `std` support in `rand_core`.
+The `std` feature is *not enabled by default*. This is primarily to avoid build
+problems where one crate implicitly requires `rand_core` with `std` support and
+another crate requires `rand` *without* `std` support. However, the `rand` crate
+continues to enable `std` support by default, both for itself and `rand_core`.
 
 The `serde1` feature can be used to derive `Serialize` and `Deserialize` for RNG
 implementations that use the `BlockRng` or `BlockRng64` wrappers.