Load torque parameter description misleading about vehicleinterfaces

[tobolar]

I think this is reasonable. But for this update we definitely need a conversion script.

So we can upgrade the model for the next major version as follows:

1. torqueLoss must be of Modelica.Mechanics.Rotational.Sources.SignTorque (probably with linear regularization for speed around zero) instead of ConstantTorque. As long as connected to an ICE, this would probably not be noticeable but I guess this is a good modelling practice since we really deal with a load which is speed sign dependent.
2. Rename parameter accessoriesLoad to tau_load.
3. Prepare conversion script for: accessoriesLoad -> -tau_load
4. The examples in VehicleInterfaces.Examples will deliver another but correct results because there is used positive value of accessoriesLoad so far. This positive value will be retained but shell work correctly like a load.
5. This will be referred in the release notes.