v0.6.0

What's Changed

TimeoutManager can now hold a Copy item (to be returned to sender) for a set amount of time:
https://github.com/knox-networks/rex-sm/blob/efb8b508209a02692a6bc4fd5d6064f54e45851c/src/timeout.rs#L172-L176

This opens the way for retry logic implementations that can re-run on a cadence without blocking StateMachine processors.

• StateMachine::process is not a sync method
• StateId is now part of the SmContext:
  https://github.com/knox-networks/rex-sm/blob/0bbc75433fa07cef1a3ff99d5fdbf6455a9db2c1/src/manager.rs#L129-L134
• Added timeout::Timeout trait for Kinds that handle timeout items:
  https://github.com/knox-networks/rex-sm/blob/efb8b508209a02692a6bc4fd5d6064f54e45851c/src/timeout.rs#L159-L166
• Added timeout::TimeoutMessage for RexMessages that handle timeoue items:
  https://github.com/knox-networks/rex-sm/blob/efb8b508209a02692a6bc4fd5d6064f54e45851c/src/timeout.rs#L150-L157