Render weighted consumption

[sander-visser]

Highlighting how good one is to avoid increasing energy use when cold and wind still, and how good one is to charge the car on cheap nights. Done by drawing a line for the region code avg consumption per day. Maybe change the unit on the left to percent, but keep showing xWh when tapping the datapoint.

If Tibber API provides energy use per class and day (how much went to vehicle charging) that would also be nice to render in separate color.