Add 'Final Round Surplus' row in summary.csv

[yezr]

RCTab Version: 1.3.999
Config vmsg surplus transfer test.json
CVR vmwg cvr.xlsx

In STV, when the final candidate(s) are elected we have a final transfer round to remove any votes over the threshold that are unneeded to elect that candidate. This step ensures that all elected candidates are shown with the same vote total in the final round (otherwise, the last candidate(s) to be elected would show a higher vote total than candidates elected before them). Currently, those surplus votes over the threshold are moved to the Inactive Ballots bucket in the final transfer round. We should make a new bucket, Final Round Surplus, under Residual Surplus, and put any surplus votes unneeded to elect in there. This would show up in both summary.csv and summary_extended.csv

I added an example below. The sum of everything in the a box should equal b. Only the final round where surplus transfers are made from the last elected candidate(s) should have a number for Final Round Surplus, others should be empty.