Alt EnergySource for Car Prototype

[fidgetwidget]

Right now it requires a burner value in the car entity prototype
It is not currently possible to create a vehicle type that either relies on the equipment grid for power, or doesn't require any power source at all.
I would love to see new energy source options (so that mod creators could add new options, not only to vehicles, but inserters, furnaces, etc), but I'd settle for being able to remove the burner property on the car prototype.

[Bilka]

It's now possible to use the void energy source in cars, so I am moving this to implemented.