fix 2.1.14 parsing by including an extra unknown field

[thejoshwolfe]

closes #6.

This makes a default settings exchange string parse without errors for Factorio 2.1.14.

I didn't find any explanation of this field in https://lua-api.factorio.com/latest/types/UnitGroupSettings.html , so i called it unknown.

[rfvgyhn]

I think unit group might not be the correct change. build_base_unit_dispatch_cooldown was added at some point which this tool doesn't currently account for. https://lua-api.factorio.com/2.1.13/types/EnemyExpansionSettings.html. It appears to account for the uint32 you've added here. It doesn't show up in https://github.com/wube/factorio-data/blob/master/map-settings.example.json though which makes it easy to miss.

[thejoshwolfe]

Yeah, i'm pretty lost in this unit group stuff. I determined where to put this new line of code by stepping through with a debugger until something parsed clearly wrong, like a float parsing as 1e-308 or something like that, and then just inserting one integer read before it.

If there's a better approach than guesswork, we should definitely be able to do better than this PR.

[rfvgyhn]

Yeah, I'm guessing it broke in unit group because that new field is part of enemy expansion which happens right before unit group and the first couple fields of unit group are the same type as the last few fields of enemy expansion.

Short of decompiling the factorio binary, I think guesswork with hints from the doc changes is our best option.

If you want to make the change in this PR I'll merge it. If you'd prefer to close this PR and open a new one I can merge that. Or I can just make the change. Whatever is easier for you with your other PR is good with me.

[rfvgyhn]

Looks like that field was added to the data repo in their latest commit. wube/factorio-data@8c37187#diff-d63ed68af1a2bdf627a00071fe54cf544ff575339461af0cd9bef43580c242bc

[rfvgyhn]

I added v2.1.13 support in 9c5bd61 by adding enemy_expansion.build_base_unit_dispatch_cooldown. Thanks for narrowing it down.