* frontlight on kobo: a few fixes
Rewritten to not update NickelConf on every change, and never
if KOBO_SYNC_BRIGHTNESS_WITH_NICKEL = false.
Reintroduce global settings frontlight_intensity and
is_frontlight_on to keep level and state across koreader
sessions.
Fix a few of the remaining issues on kobo light.
Ensure settings are saved when rebooting/powering off from
File browser.
* Ensure untoggle works when starting with light off
* Put back fl_min=0 as it is for all other devices (the idea
fl_min should be 1 and toggling managed some other way is
not implemented in current code).
* Fix a few frontlightwidget issues
* Use PluginShare to exchange data between plugins
* Remove legacy code in reader.lua and kobo/device.lua, and move KOBO_LIGHT_ON_START to kobo/powerd.lua
* A better sync config logic
* Consider kobo without hardware frontlight toggle
* update frontlight widget once toggle is tapped.
* 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()
Disable wakeup_count handling, that's often causing more harm than
anything else...
Nickel doesn't even use it, that should have been a hint ;).
Make the logging slightly less confusing.
Add commented out debug features (dumping relevant dmesg output).
Re #2188
