This adds a new `std` feature to chrono that is enabled by default. By
deactivating this feature via `default-features = false` you can now use
chrono in applications that don't use the standard library. The `serde`
feature is supported as well.
Resolves#336
Rather than the `num` meta-crate, use `num-integer` and `num-traits`
without default features to make them `#[no_std]`. `num-iter` is
just a dev-dependency now for a few test cases.
The only public change is the `impl FromPrimitive for Weekday`, but this
is still the same exact trait that `num` re-exports, so this is not a
breaking change.
Now (assuming clippy is right) all (~100) uses of ` as ` in the code are
actually doing casts that could potentially silently lose data. Woooo?
At least this means that new `as`s can be extra-scrutinized, and we should
probably be adding debug_assert!s for the casts in real code.
