Fixed potential bug that could prevent sudden undervoltage detection

due to a short circuit and removed makeshift NiCd battery support.

Bugfix in release script

Remove unused submodule

Updated version number

Fixed file name capitalization error

Print current state in the system status

Also increase PWM update interval to 20 ADC cycles

Update li-charger-schematic.png

Update README.md

Reduce error recovery timeout

Refactoring