I don't actually know how temporary this one is going to be. The usages
are quite deep - ie. converting to a `ScoreInfo` to get a calculated
total score for ordering purposes.
Not the most obvious keys, but does match stable expectations so let's
go with it for now.
Rationale for not using +/- is that local audio offset was bound to
those, and people will expect it to be when we get to implementing
eventually.
Also, adjust the scroll speed is a pretty rare thing to do since it's
been constant across beatmaps for years now.