BurnerPrototype::fuel_categories

[Therax]

I'd like to be able to specify multiple fuel categories that a burner is capable of consuming, accepting any fuel that belongs to any listed category.

As an example use case, XanderMod (viewtopic.php?f=97&t=51868) has two forms of burner inserter, one that consumes crude chemical fuels like wood, and another that requires pure chemical fuels like charcoal. The former is necessary in the early game before pure chemical fuels are available, and the latter exists because there are furnaces that require the charcoal, and it's convenient to use a burner inserter that can feed itself using that fuel. The mod would really prefer a single burner inserter entity that could consume either.

[Rseding91]

Ok, I've changed it for 0.16 so you can define multiple fuel categories.