making arbitratorExtraDataId 64 bits instead of 32 meant that DisputeSlot struct needs more slots, which is awkward.
turns out that the aparent sole reason we stored arbitratorExtraDataId in DisputeSlot was to make appeals. But stake-curate doesn't bother with that anymore, so it can be removed
making arbitratorExtraDataId 64 bits instead of 32 meant that DisputeSlot struct needs more slots, which is awkward. turns out that the aparent sole reason we stored arbitratorExtraDataId in DisputeSlot was to make appeals. But stake-curate doesn't bother with that anymore, so it can be removed