Custom Piano Labels

https://github.com/LMMS/lmms/blob/7c6ade5736c04661a0e47da4112a74197a49b7b6/src/gui/editors/PianoRoll.cpp#L133

Representation↓ Keys →| C | C# | D | D# | E | F | F# | G | G# | A | A# | B | Notes
-- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | --
English | C | C# | D | D# | E | F | F# | G | G# | A | A# | B | Currently in use
SARGAM short form | S | r | R | g | G | m | M | P | d | D | n | N | Use case 1
Classical सरगम | सा | .रे | रे | .ग | ग | म | म' | प | .ध | ध | ऩि | नि | Use case 2 (needs to rewrite the symbols)

Notations for classical in the example above are not fully correct.
Notations in other systems to be addressed as well.

It would be fantastic if one can change the piano labels to custom labels as used in many other practices.
The table above shows some basic replacements (what to replace with). The table may not be exact at the moment.


Many authors (tutors in particular) use their notes/labels for comfort. But while it comes to data-entry the existing notes in LMMS; it is confusing to see English Labels only. It would help a beginner do the data entry so easily, if the custom labels were possible.

Spreadsheet File attached:
[custom-labels.ods](https://github.com/LMMS/lmms/files/7179228/custom-labels.ods)

---
Related articles:

* [How music theory works in different countries](https://www.classicfm.com/discover-music/music-theory/music-theory-different-countries/)
* [Key signature names and translations](https://en.wikipedia.org/wiki/Key_signature_names_and_translations)
* [Solfège](https://en.wikipedia.org/wiki/Solfège)
* [Svara](https://en.wikipedia.org/wiki/Svara) - concept in classical music

Usages of the symbols:
* [Comprehensive list of Raags in symbols](https://www.sharda.org/raga-taal/)
* [Simple Raag Player](http://heyizhou.net/page/raag-player)

Start in src/gui/editors/PianoRoll.cpp around line 133, where the piano labels are referenced. First determine how those labels are currently generated and how custom label schemes would be selected; the issue's examples are explicitly incomplete. Done means the piano roll can display user-selected labels for the intended notation systems, with the supported symbols and behavior agreed upon.

Written by the indexing model from the issue text.