Fuel tracking has issues

[KirkMcDonald]

For example, smelting iron with nuclear fuel doesn't produce a correct result. This is because there is a circular dependency of sorts, between the uranium subgraph and iron plate, and the tracking of fuel usage doesn't recalculate the recipe subgroups.

Another example would be smelting copper plate by burning small electric poles. This has been explicitly disabled, as the current version of the code causes an infinite loop.

The solution is to recompute the recipe subgraphs when needed. Specifically, when:

• The furnace is changed from one that needs fuel to one that does not, or vice versa.
• The preferred fuel is changed while the furnace is set to one that needs fuel.

[KirkMcDonald]

Fixed in 1064da5bedc17ca2246cd45c2fd8481d540af19f.