* Implement builder pattern for cargo command-line args, refactoring
* Add an `xtask` subcommand to build a package (not its examples)
* Add an `xtask` subcommand to bump the versions of packages
* Fix a silly mistake from the initial implementation
* Improve the `build-examples` subcommand, make it usable with other packages
* Add a `build-documentation` subcommand
* Update `README.md`
* Add toolchain modifier when required
* Create the `xtask` package, add command for building examples
* Do not perform changelog check for `xtask` package changes
* Fix unrelated `rustfmt` error