Partial, as it will safe the state when suspending the reader by pressing the power-button.
However, it will still not safe the state when Pocketbooks autoPowerOff-Feature kicks in, as this does not create an event (e.g. no EVT_BACKGROUND) of any kind.
* Clean up device.lua
* Save state on suspend
* Start battery stat plugin
* BatteryStat & kobolight
* Several minor improvements
* Remove a useless function
* flush settings
* Some review feedbacks
* Resolve review comments
* Remaining Minutes -> Remaining Hours
* Add dump_file
* typo
* realpath
* realpath on folder
* Remove useless os.time()
* Resolve review comments
* warning
* Add BatteryStat.debugging flag
* treat log as txt
* Minor improvement
* Charging hour should be positive
* Use warn instead of info
* onSuspend in Kobo
* Charging events for kobo and kindle
* More events
* dumpOrLog
* Warnings
* Typo
* More space
* Singleton
* slightly format change
* BatteryStat singleton
* Init
* Remove debugging flag
* sleeping percentage is still negative
* Read settings
* Do not need to change was_suspending and was_charging
* Typo
* Remove debugging flag
* Not charging should happen before suspend
* Resolve review comments
* was_suspend and was_charging should be updated each time in onCallback()
