* Prefer third-party plugin development in plugins instead of kibana-extra
* Fix failing recursive directory creation and removal
* Add new built version of kbn-pm
We need to share `@kbn/datemath` with `@elastic/eui`, and rather than making them rely on Kibana for their dependencies we've decided to republish `@kbn/datemath` as `@elastic/datemath`. This isn't something we want to do often, so please check with the platform team if you'd like to do this for another module.