Added icon for when the device is charging
Created by: IanS5
This PR is pretty big just because the icon required a bunch of new draw functions, since it's the first one (i.e. the only one except the battery) that isn't just a bunch of rectangles.
When the device is charging it shows a little lightning bolt in the top left corner of the screen. If the -c
flag is set than it will attempt to show the current too.