applets: split battery and brightness, and integrate night color into brightness
See the discussion in #93 (closed).
The first commit is the split, with some adaptions.
The night color row in the second commit is all new on the QML side, with the main part of the plugin taken from the applet that currently lives in kdeplasma-addons, which should then be removed.
Depends on: kwin!4616 (merged)
See also: !3503 (merged)
Closes: #93 (closed)
Edited by Natalie Clarius