Change Log ==== 0.3.6: * Add serde (de)serialisation support (`--features=serde`) * Optionally use a `BTreeMap` instead of a `HashMap` as the backing map (`--features=btreemap`) 0.3.5: * Enable README rendering on crates.io (no code changes). 0.3.4: * Allow keys to have lifetimes other than 'static.