[fb] Numbers with more than two accidentals are ignored

[WolfgangDrescher]

**kern	**kern
*clefF4	*clefG2
4c	4cc
4c	4b-
4c	4a#
4c	4g--
4c	4f##
4c	4e---
4c	4d###
4c	4c
=	=
*-	*-

[craigsapp]

You have some music with triple sharps/flats? 😉

Obviously you are writing the documentation now...

This is fixable but it takes more work than you might expect to do it correctly: (1) I could count the sharps/flats for each interval and then a sequence of single flat/sharps (or combinations and mixtures with double sharps/flats). (2) I typically calculate intervals and accidentals using the Base-40 system, which is limited to double sharps/flats, so any use of Base-40 for calculations in display of **fb or in fb calculations would have to be changed.

Case (1) is easy to implement, but Case (2) may or may not be easy. Ideally I would steal the Transposer class from verovio:

https://github.com/rism-digital/verovio/blob/develop/include/vrv/transposition.h
https://github.com/rism-digital/verovio/blob/develop/src/transposition.cpp

Where this is a high-accidental variant of the Base-40 system called "Base-600" which allows up to 42-sharps/flats. Then this can be an interface to interval transpositions which is easy to switch between base-40 or base-60 (or any other variant of the system depending on how many accidentals you want to handle).