Update Bach BWV-988 var14

bar4: in treble clef, first "e" should be "f"
(Steve Shorter)
Fix beaming slopes
Bars 10,11,12: update first bass note to 16th
Bars 13,14,30: add staccato to single eigths
Bar19: bass start slur fis->a
Update to v 2.16.1
(Javier Ruiz-Alma)
Close #64