New field: Completionist / CompletionDate #15
Description
Currently there's no way to canonically store who completed the work, if someone other than the composer did so.
Hacks include storing both names in the composer field (e.g. Mozart/Süssmayr), or adding the completionist as some sort of a performer.
A Completionist field (with a data type analogous to Composer) would solve this problem neatly.
When used in conjunction with a new field CompletionDate, we can mark the year in which the sketch was written separately from when that sketch was completed.