* Don't write storage to disk while stopping
* rework change
* lint
* remove delay save and schedule final write at stop
* update tests
* fix test component using private methods
* cleanup
* always listen
* use stop in restore state again
* whitelist JSON exceptions for later
* review comment
* make zwave tests use mock storage
* add third stage to hass shutdown
* use 3rd stage in storage
* update core state
* add writing data to multi stop ignore
* update core test
* review comment
* update name based on feedback
* Allow managing Lovelace storage dashboards
* Make sure we do not allow duplicate url paths
* Allow setting sidebar to None
* Fix tests
* Delete storage file on delete
* List all dashboards
* Type check all helpers, add inline exclusions for work in progress
* Remove unused Script._template_cache
* Add some missing type hints
* Remove unneeded type: ignore
* Type hint fixes
* Mypy assistance tweaks
* Don't look for None in deprecated config "at most once" check
* Avoid None name slugify attempt when generating entity id
* Avoid None state store attempt on entity remove
* Restore states through a JSON store
* Accept entity_id directly in restore state helper
* Keep states stored between runs for a limited time
* Remove warning
* Addded support for private storage.
Include 'private' flag parameters to the Store class and save_json function.
Updated various authentication and onboarding classes to use private stores.
Fixed unit test for emulated_hue which used a mock patch on save_json().
* Fixed Hound formatting issues not detected by local linting.
## Description:
Make typing checks more strict: add `--strict-optional` flag that forbids implicit None return type. This flag will become default in the next version of mypy (0.600)
Add `homeassistant/util/` to checked dirs.
## Checklist:
- [x] The code change is tested and works locally.
- [x] Local tests pass with `tox`. **Your PR cannot be merged unless tests pass**
* Add storage helper
* Migrate config entries to use the storage helper
* Make sure tests do not do I/O
* Lint
* Add versions to stored data
* Add more instance variables
* Make migrator load config if nothing to migrate
* Address comments
Franck Nijhof
Marc Mueller
tkdrob
J. Nick Koston
Ville Skyttä
Paulus Schoutsen
David F. Mulcahey
Bas Nijholt
Franck Nijhof
Adam Mills
Paulus Schoutsen
Nicko van Someren
Paulus Schoutsen
Andrey