Add consumption while idling

[PaulScheerRLI]

Right now consumption is calculated using the trip distance and the consumption per distance.
Consumption during idling, e.g. while at a stop or terminus, is not considered. In winter or summer times with harsh AC loads, this can lead to an under estimation of consumption. This could be fixed by enhancing the consumption calculation of a trip by adding the idling consumption.

[j-brendel]

@PaulScheerRLI Do you have an idea how to implement this? We will need this now.