Update Bach BWV 988 var25

Bar 24: 'aes' in bass should time to 'aes' in bar 25
(Steve Shorter)
Bar 25: eigth notes on first beat should be slurred
(Felix Janda)
Update to v2.16.1
Slur and appoggiatura direction updates
Reposition polyphony rests
Force display of accidentals to match source
Bar 5: 1st grace note e->ees, 'as16 as32'->'as16 ~ as32'
Bar 6: treble bes16.->bes16 ~ bes32
Bar 13: treble "\grace a16" -> "\appoggiatura a16"
Bar 14: treble "\grace a16" -> "\grace c16"
Bar 16: treble add slurs between cis and d for both volta alternatives
Bar 17: treble "\appoggiatura  c16"->"\appoggiatura  bes16"
Bar 21: treble "\appoggiatura c16" -> "\appoggiatura ces16"
Bar 24: bass first note "a"->"as"
Bar 32: add termination bar
Bar 34: bass, correct tie first note of second volta alternative
(Javier Ruiz-Alma)
Close #55