[Sparsey] by [@LechintanTudor] is a sparse set-based Entity Component System

(ECS) with component storage grouping, granular component change detection,

fallible systems and beautiful syntax.

The latest release (0.4) adds support for optional system parameters, which

allows `Option<Res<T>>` and `Option<ResMut<T>>` to be used in system functions.

This release also features a refactored `ComponentStorage` which makes adding,

removing and swapping components faster, swapping being especially important

since it enables component grouping, a features that makes certain queries

specified by the user extremely fast.

Finally, some implementation details were hidden from the public API and the

`#[must_use]` attribute was added to functions whose results should not be

discarded.

[Sparsey]: https://github.com/LechintanTudor/sparsey

[@LechintanTudor]: https://github.com/LechintanTudor