RogerSelwyn/O365-HomeAssistant v4.0.0b4 on GitHub

alt_auth_flow has been removed as a valid configuration parameter. This has been deprecated for 6 months. See here for details of how to configure alt_auth_method to meet your needs.
calendar_id is no longer supported as a parameter in service calls. entity_id should be used instead. Overall the changes to service calls in this release improve validation and should make it clearer when calling the service as to what a problem might be if one occurs. It also significantly simplifies the code which will benefit future changes.
The location of the o365 token and o365_calendar.yaml files have been moved under the o365_storage directory. This helps to group the various o365 files in one place. If you are backing up your configuration to a public GitHub, you will need to change your .gitignore.

The Secondary/Legacy method of configuration has been marked as deprecated and will be removed in a future release. See here for more details on how to perform the migration.

Meaningful icons have been added to all sensors. Thanks to @rdeveen for prompting the change.
Tasks/Todo sensors can be enabled. See Configuration for details.

Full list of changes