Improve GenEvent.stream/2 cleanup

Makes the cleanup of the Stream resource more efficient by reusing the
monitored process and its link to ensure the handler has been removed.

The flushing of messages, after removing the handler, is also only done
when needed.
Merge pull request #2423 from fishcakez/genevent_stream_stop

Improve GenEvent.stream/2 cleanup
Start epmd, clean up warnings
Update CHANGELOG
Release v0.14.1
Start v0.14.2-dev
Remove previously deprecated behaviour
Fix wrong changelog entry