--quote-title flag, fixed warning, Rust 2021, bumped deps, cargo fmt

[virtualritz]

I added a --quote-title flag since I and some other crate authors like to have their crate title as

foo

rather than

foo

This includes a test for this feature.

While on it I also:

• Ran cargo fix --edition twice to change the code from Rust 2015 to Rust 2018 to Rust 2021.
• Fixed a warning about replacing Vec::split_off() with Vec::truncate().
• Ran cargo fmt.
• Bumped all dependencies to the highest versions that didn't require further code changes (as e.g. clap 3.0 would have)