Auto calibration support

[uzza1hossain]

Thanks for the neat and clean package.

It would be excellent to have a system where users can set an interval, let's say 7-days. Afterward, every 7 days, it will automatically charge up to 100 (no matter the limit define by user), then discharge to 15, and finally recharge to the user-defined limit.

The flow will be like.

1. Keep track of the last calibration.
2. Check if the last calibration was 7 days ago or more.
3. If it's been more than 7 days, set the limit to 100%.
4. When it reaches a 100% charge, disable the adapter.
5. When it drops to 15%, enable the adapter.
6. Set the limit to the user-defined value.
7. Update the last calibration time.