Add "no_std supported" badge to readme

Bump crate version to 0.4.1

Bump crate version to 0.4.0

Merge pull request #11 from slowli/prepare-v0.3.0

Prepare release 0.3.0

Properly mark minimum supported Rust version

Rename features

crates.io doesn't like feature names encoded as strings, apparently.

Bump version to 0.1.1

Add metadata to `Cargo.toml`