command-group

• Use std's process_group() (#16).

• Change UnixChildExt::signal to take &self instead of &mut self.
• Grouped child waits using upstream ::wait and ::try_wait in addition to the internal pgid-based logic, to help with cancellation.
• Optimisations in tokio::Child::wait(). (#25, #26)

• Add ErasedChild::id() method.

• Clarify why and in which situations AsyncGroupChild::wait may not behave as expected when cancelled.
• Add AsyncGroupChild::start_kill to align with Tokio's Child::start_kill.
• Change AsyncGroupChild::kill to also wait() on the child, to align with Tokio's Child::kill.
• Add ErasedChild abstraction to allow using the same type for grouped and ungrouped children.

• Update nix to 0.27.
• Increase MSRV to 1.68 (within policy).
• Add note to documentation for Tokio Child::wait wrt cancel safety. (#21)

(Same as 3.0.0, but yanked due to breakage.)

• Add new .group() builder API to allow setting Windows flags and use kill_on_drop. (#15, #17, #18)

• Fix bug on Windows where the wrong pointer was being null checked, leading to timeout errors. (#13)

• Increase MSRV to 1.60.0 and change policy for increasing it (no longer a breaking change).
• Wait for all processes in the process group, avoiding zombies. (#7)
• Update nix to 0.26 and limit features. (#8)

• Bugfix: compiling would fail when Tokio was missing the io-util feature (not io-std).

• Bugfix: compiling would fail when Tokio was missing the io-std feature.

• Correctly handle timeouts on Windows. (#2, #3)

• Internal: change usage of feature = "tokio" to feature = "with-tokio".
• Documentation: remove wrong mention of blocking reads on AsyncGroupChild::wait_with_output().

New: Tokio implementation, gated on the with-tokio feature.

Bugfix: GroupChild::try_wait() would error if called after a child exited by itself.

Bugfix: GroupChild::try_wait() and ::wait() could not be called twice.

Implement Send+Sync on GroupChild on Windows, and add a Drop implementation to close handles too (whoops). Do our best when .into_inner() is used...

Initial release