`std::async` API

Thiefpool now follows the std::async interface copying arguments by default. Additionally, we have included promise's exception handling.

Random stealing

Non-deterministic stealing helps to avoid contention, additionally a small spin upon thread release (trying to get work from own queue) helps to prevent contention.

Detached enqueuing

v1.2.1

release-acquire ordering

Initial release

v1.0.0

v1.0.0