Fix chord annotations and add multivoice spine splits
This PR corrects annotation errors found in the dataset:
Chord symbols encoded as !LO:TX text layout annotations instead of in the **mxhm spine
- LO:TX chord annotation fixes
In 14 pages, chord symbols were incorrectly encoded as humdrum local text layout annotations (!LO:TX:a:t=CHORD) rather than in the **mxhm harmony spine. This caused the chord to appear as a text overlay in rendering but be invisible to any OMR or music analysis system reading the **mxhm column.
Before:
!LO:TX:a:t=Bmi7 !
2b_ .
After:
2b_ B:min7
Affected pages and corrections:
Page System Encoded text Corrected **mxhm
slow-hot-wind.jpg 4 Bmi7 B:min7
slow-hot-wind.jpg 4 E7-9 E:7(b9)
slow-hot-wind.jpg 5 Dmi9 D:min9
moon-river.jpg 2 Eb(#11) Eb:maj(#11)
phase-dance.jpg 1,3,5 Bb^(#11) Bb:maj(#11)
how-deep-is-the-ocean_v1.jpg 4 G +/B G:aug/B
four.jpg 7 Ebm Eb:min
st-thomas.jpg 2 Em7(b5) Em:min7(b5)
st-thomas.jpg 2 Ab7(#5) Ab:7(#5)
mamacita.jpg 3 C7(#9) C:7(#9)
mamacita.jpg 3 Bb7(#9) Bb:7(#9)
speak-no-evil_v1.jpg 2 A-7b5 A:hdim7
oleo.jpg 2 Gmu7 G:min7
miyako.jpg 3 amj7 A:maj7
sophisticated-lady.jpg 3,4 D7(b9), F7(b9) D:7(b9), F:7(b9)
last-train-home.jpg 1,4 F7sus4, Eb6#11 F:sus4(7), Eb:6(#11)
happy-holiday.jpg 7 Bb6 Bb:6
moment-to-moment.jpg 0 Am A:min
Some !LO:TX lines contained non-chord symbols (navigation markers like D.S. al Coda, Coda, To Coda, tempo markings, segno/coda glyphs) — these were left untouched.
A small number of entries (in-a-sentimental-mood.jpg) contained !LO:TX lines with chord-like text that on inspection referred to decorative notation artifacts and were deleted without adding to **mxhm.
- Cleared erroneous chords from four.jpg system 6
System 6 of four.jpg contained chord annotations in **mxhm that do not correspond to anything in the image (writing error during annotation). All chord values in that system were cleared to ..
Reverted spine splits
An earlier version of this PR incorrectly added *^ spine splits to encode simultaneous notes. This was a mistake — space-separated tokens (e.g., 4cc#X 4ee) are already valid kern chord notation. All *^ additions have been reverted. The *^ count is identical between the original and cleaned synthetic dataset.
All changes are applied consistently to both the system-level **kern fields and the full-page encodings['**kern'] field.