Resolves YES if by 12/31 it is possible for an author to undo a market resolution. Any capability to undo (even if it's just a few seconds) will count for the purposes of this market.

Motivation: People accidentally resolve markets incorrectly sometimes. This is a recent real-world example: 

https://manifold.markets/Austin/what-contributions-will-we-list-on#Df3a0jEtLDQ9qEJKQO1Y

. I think it would be good if the author can undo the resolution of their market. This would undo all of the payouts made by the incorrect resolution (undoing transactions is not a new concept, it's similar to how N/A undos all of the trades). Then the author can resolve to the correct resolution, or the market can stay open if it wasn't supposed to be resolved yet. This should probably be subject to reasonable limitations - e.g. can only fix the resolution within some grace period. Perhaps in the future it could require approval by other parties. But I think given that authors freely editing markets was added without any issue, allowing authors to undo resolution shortly after an accidental mistake would be much more likely to allow fixing mistakes than to be abused.