This is an improvement and bugfix release.

Improvements

• Add fork_join operator #533
• Allow AsyncIOThreadSafeScheduler to schedule on its own AsyncIO event loop #567

Fixes

• Fix InvalidStateError in to_future #529
• Complete as soon as any source completed In zip #525
• Fix delay_with_mapper subscription #547
• Fix scheduler forwarding in delay operator #555

Other

• Do not use pytest-runner #522