Reolink-aio

- Fix get_state for unkown command

- Add ONVIF_event_callback method
- Add flv protocol stream
- Add visitor_detected method
- Add host setting commands to get_state
- Add username and user_level properties

- Improve ai_supported property
- Simplify ai_detected method
- Improve motion detection state
- Improve logging
- Remove unneeded setters

**Full Changelog**: https://github.com/starkillerOG/reolink_aio/compare/0.2.0...0.2.1

Improve get states:
- Add GetEvents to get_states command
- Fix GetPowerLed returns incorrect channel
- Improve recognition of PTZ control capabilities
- Only request GetAlarm PTZ/zoom/autofocus when supported

- Fix get_state function
- Improve debugging of map_channel_json_response

Initial release

Based on https://github.com/JimStar/reolink_ip

- Implement retry on JSON decode error and 502 errors
- Reduce API calls by requesting all channels at once instead of looping
- Include new GetEvents command to also poll for doorbell presses