Show ingredient alternatives in flat crafting plan

[rubensworks]

Issue type:

• ➕ Feature request

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Short description:

In the tree-based crafting plan, ingredient alternatives are shown.
However, in the flattened plan, these are not shown, while it would be nice if they would.

This will need some changes in IndexedEntries, as they are now indexed by IPrototypedIngredient, while this should be changed to should be IPrototypedIngredientAlternatives (or something similar).
We can then make the GUI rotate over these alternatives, just like the tree-based plan.

[rubensworks]

Thanks for the suggestion!