[String] and [Vec] both use the heap. Switch to [&str] and [&\[u8\]] where possible to better support embedded clients. [String]: https://doc.rust-lang.org/std/string/struct.String.html [Vec]: https://doc.rust-lang.org/std/vec/struct.Vec.html [&str]: https://doc.rust-lang.org/std/primitive.str.html [&\[u8\]]: https://doc.rust-lang.org/std/primitive.u8.html
