Make BWG088 corrections as requested by @dominicus

I don't know anything about this piece so I can't vouch that the changes are
correct, but I thought I would create a pull request. In accordance with issue

I checked these against the Open Goldberg Variations edition. The first
correction would make us match their edition, the second correction would make
us diverge from their edition.
Merge branch 'issue-106' of https://github.com/captbaritone/The-Mutopia-Project
Update footer, and correct bar 22 to be consistent with the Open Goldberg Variations edition