Fixes #4932: Allow plugins to be saved in entity cache
Merge pull request #443 from mrclay/4932-18

Fixes #4932: Allow plugins to be saved in entity cache
Bumped version to 1.8.10. Updated changes. Refs #4947.
Merge commit '8b6ef5a2081e0436a5135e8cfa954fd3ab158282' into tmp_merge