Roll back game versions instead of deleting them

[dfabulich]

When viewing update history, moderators have the option to "Delete Version," which deletes the version from history completely; there's no way to get the deleted version back out of history (except, I suppose, to fish it out of a backup).

There should be an option to "roll back" a version. This would create a new version on top of existing versions, setting all of the data back the way it was, but preserving it in history.

[dfabulich]

Maybe all users should be allowed to "roll back" game versions, but only moderators should be allowed to roll them back? (Anyone could roll back a game just by carefully copying and pasting data from a previous version, right?)