Posthog

- Support for sending feature flags with capture calls

- Support multi variate feature flags

- Allow feature flags usage without project_api_key

- Fix packaging issues with Sentry integrations

- Improve support for `project_api_key` (32)
- Resolve polling issues with feature flags (29)
- Add Sentry (and Sentry+Django) integrations (13)
- Fix feature flag issue with no percentage rollout (30)

- Add `$set` and `$set_once` support (23)
- Add distinct ID to `$create_alias` event (27)
- Add `UUID` to `ID_TYPES` (26)