[feature] Add option to generate notifications at selected battery percentages

[dillburt]

In order to maximize the service life of my battery, I'd like to try to keep it in the 20%-80% charge range as much as possible. I haven't found any tools to help implement that strategy, so I'm trying to do it manually. When charging, disconnect charger when charge level reaches ~80%. When discharging, connect charger when charge level reaches 20% (if not before).

It would be helpful if BBS could generate notifications for these charge/discharge thresholds, to remind me to connect/disconnect the charger.

I know this is a little outside the scope of the core features of BBS, but it might be popular with the target audience of BBS. If it could be implemented fairly easily, and without increasing the battery usage of BBS, then it might be worth considering. Thanks.