Created by: towo
Patch to add feature for reading out the state of multiple batteries. Uses a combined percentage of last full charge capacities to deduce the current system overall battery level.
Essentially: (battery0_percentage * battery0_capacity + battery1_percentage * battery1_capacity + [...])/(battery0_capacity + battery1_capacity + ...)
Might include some small rounding errors due to using bc
at scale 2 to get the floating point parts of the calculation.
Rebased from master to develop, for full disclosure.
This would resolve nojhan/liquidprompt#393