Define fuel for burner energy sources

[darkfrei]

Hi. It will be good to define what the fuel is possible to use by some burners. For example, very powerful assembling machine with boiler like an energy source, which can burn only rocket fuel.

Coal and wood are too easy for rocket assembler or rocket furnace.

[orzelek]

Fuel category already exists so this is possible now.
Take a look at nuclear reactor and it's burner definition.