Managed to reproduce https://github.com/celluloid/celluloid/issues/443 occasionally.
Update to timers 4.0.0.
Use timers instead of Time#now.
Receivers uses parent Actor's @timers, simplifies Actor#run.
Change to Timers::Group#wait.
Split #receive into #check and #receive. Use #check in Actor#run.
Remove TimeoutError handler, not used in #check.
Merge pull request #451 from ioquatix/update-timers

Update timers