Automatically compute contest outcomes from ballot manifests

[ranweiler]

The Dominion ballot manifest contains sufficient information to directly compute candidate shares for all contests.

• Add backend code to compute the per-contest shares
• Expose computed shares to frontend
• Automatically populate contest/candidate share fields from the derived computation

Questions:

• Should the computed shares be overrideable by users? Under what circumstances?
• Is it (always) appropriate to derive vote shares from the ballot manifest?

[ranweiler]

CC @nealmcb, @kiniry.

[nealmcb]

I'd call them margins, both in absolute ballots, and in percentages. Not in a range 0-1. I don't think users will override margins by manual entry. In fact they won't want to do just about anything per-contest by manual entry - too many contests.... But they certainly will want to be able to input margins which are different than the set of CVRs they have. These will come from the state-wide Election Reporting system, and may be modified by numbers of ballots that are uncounted (to be considered as a best-case for the loser) etc.