Add turkish AEU accidentals to data.ACCIDENTAL.GESTURAL

[annplaksin]

This is the sequel PR to #720 :
Since the aeu accidental values cannot be expressed with the already existing values of data.ACCIDENTAL.GESTURAL, it would be very helpful to add them as gestural values too.

I splitted data.ACCIDENTAL.GESTURAL as it has been done for written accidentals in #720 and added the aeu accidentals. To avoid the duplication of data types, I renamed data.ACCIDENTAL.WRITTEN.aeu to data.ACCIDENTAL.aeu.

A corrected version of the aeu accidental value overview has been added as well.

[kepper]

didn't compile to see if the image links work, but other than that seems plausible – thanks for the work on that 👍

[kepper]

thanks for your work on this, @annplaksin 👍

[rettinghaus]

Sorry for me complaining about this so late, but even if AEU accidentals would have be the same in gestural and visual domain, I don't think we should combine them nto data.ACCIDENTAL.aeu, as this breaks current naming (and basically the current schema). I would prefer to keep data.ACCIDENTAL.WRITTEN.aeu and add data.ACCIDENTAL.GESTURAL.aeu instead.

[annplaksin]

You have either a break of naming or redundancy. I asked @kepper before I made the pull request if this naming is okay. He didn't complain.

[kepper]

I'm certainly not the the person to decide what is right or wrong here – MEI is a community thing, and we should move forward by consensus whenever possible. I think this is a legitimate question, though, and while I refuse to be any more relevant for the decision than anyone else, I think there are arguments that @annplaksin's implementation is actually consistent with existing MEI.

In CWMN accidentals, we see a certain amount of duplication of visual values: x is two half-tones up, as is ss. For gestural purposes, there's no difference between them, though. This difference legitimates to have two separate data types for the two domains. In the list suggested by @annplaksin, there is no similar duplication of values. Accordingly, we don't need to split this up by domain. I think this is conforming to other situations in MEI. The data.DURATION.cmn data type is used by both data.DURATION (applies to @dur) and data.DURATION.gestural (applies to @dur.ges) – as the values apply to both categories alike.

I think we all agree that MEI is a "grown" model that isn't perfectly consistent across all of its parts. In this particular situation, I think we're safely within the "usual range", though – but this is definitely something to discuss and negotiate…