jeanphilippeD

Fix protobuf dependency invalid semver for cargo 1.54 for v0.5.x

2

With this, https://github.com/rust-lang/cargo/pull/9508, the dependency can no longer be used. What was picked with 1.53 cargo was ~2.0, so use that instead. **This needs to be a new branch 0.5.1...

2018 Edition: Chapter 19: Returning Closures suggest Box and not impl trait

1

Hello, I searched the issues but did not find an existing relevant one. The only provided solution for returning closure in this section is using Box: https://doc.rust-lang.org/book/2018-edition/ch19-05-advanced-functions-and-closures.html#returning-closures ``` fn returns_closure()...