Improve differentiation of vehicle types in land transport

[nworbmot]

Currently the energy demand and time series for different vehicles in land transport are merged. These should be separated into vehicle types (motorbikes, passenger cars, light trucks, heavy trucks, buses, etc.) so that we can have different transition pathways (e.g. later switch to BEV in heavy trucks) and endogenous transport transformation (see open endogenous transport issue).
Both the energy demands and time series for transport demand are already separated before they are merged, so this shouldn't be so difficult. There are additional data sources in the endogenous transport issue.

[martavp]

We at Aarhus are working on an implementation of this together with a suggestion for endogenizing transport.