Consistent instrument naming on voices.

[MarkGotham]

In fixing cases of empty text files issue (due to not finding voice parts), I'm reminded that the early days of this project saw us use Oboe in place of Voice for playback reasons.

We should correct that now, right?

Moreover, I note the following cases beyond Voice and Oboe:

• Schubert,_Franz/Op.60/1_Greisengesang,_D.778/lc4982505.mxl, (previously, now manually fixed during exploration)
• Schubert,_Franz/4_Gesänge_aus_„Wilhelm_Meister“,_D.877/1_Mignon_und_der_Harfner/lc5093434.mxl,
• Schubert,_Franz/Op.52/3_Bootgesang,_D.835/lc6181050.mxl,
• Lehmann,_Liza/Songs_of_Love_and_Spring/02_When_Young_Love_Comes_Knocking/lc6758594.mxl,
• Lehmann,_Liza/Songs_of_Love_and_Spring/06a_Golden_Bridges/lc6760929.mxl,
• Lehmann,_Liza/Songs_of_Love_and_Spring/09_My_Secret/lc6764874.mxl,
• Lehmann,_Liza/Songs_of_Love_and_Spring/06b_A_Dream_of_Violets/lc6761202.mxl,
• Gail,_Sophie/_/Le_serment/lc6604249.mxl,
• Kralik,_Mathilde/Jugend-Lieder/00_Einleitung/lc6166579.mxl,
• Holmès,_Augusta_Mary_Anne/_/Viens!/lc6174723.mxl,
• Brahms,_Johannes/4_Serious_Songs,_Op.121/2_Ich_wandte_mich_und_sahe/lc6686901.mxl,
• Brahms,_Johannes/4_Serious_Songs,_Op.121/1_Denn_es_gehet_dem_Menschen_wie_dem_Vieh/lc6686592.mxl,
• Brahms,_Johannes/4_Serious_Songs,_Op.121/3_O_Tod,_wie_bitter_bist_du!/lc6686980.mxl,
• Brahms,_Johannes/4_Serious_Songs,_Op.121/4_Wenn_ich_mit_Menschen-_und_mit_Engelzungen_redete/lc6687153.mxl

[Budimba]

Instruments were already sorted out and added to the database.

[MarkGotham]

But "sorted out" does not involve changes to the score?

[Budimba]

In different scores one instrument can go by different names (e.g., Voice = Chant = Gesang = Singstimme), and I think that's fine: technical convenience shouldn't be at the sacrifice of diversity.
For those songs with 'Oboe' etc., I looked at them and none actually displays 'Oboe' on the score, so I'm reluctant to change them. (And 'Flute' is legitimate flute accompanying the voice.)
When adding a song to the database (that's before transcription), the person will be asked to fill in the instruments in standard language (e.g., just 'Voice', no 'Chant' etc.) if it's not Voice + Piano, so scraping the existing scores will no longer be necessary. Standard language makes maintenance convenient, but the end user doesn't see the database.
One more reason to avoid scraping the scores anymore is that some songs have alternative melodies, and those have been done (correctly) with an additional, smaller, muted vocal line. In the future I may hide those staves without notes to save space.

The standard language I used is as follows:
Voice
Piano (not Pianoforte)
Cello (not Violoncello)
Guitar
Flute
Harp
Harpsichord
Viola
Soprano
Alto
Tenor
Bass
Contralto
Multiple instruments of the same type: n