Resolution of ordering conflicts is probably too liberal

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Right now, all type members are considered unordered. This isn't actually the case as fields may have dependencies on other fields, and so their order does matter.

Really, an ordering conflict can only be trivially automatically resolved if at most one of the conflicting node lists contains fields. If both contain fields, one has to analyze the dependencies between these fields.

It will probably work out quite often in practice regardless, but it would be better if fields were treated with more care.