AccidentalCalculator: Fix natural accidentals not remembered within measure

[chbauman]

Adresses and fixes #1383

Now it looks like this:

[sschmidTU]

Hey @chbauman, thanks for the contribution, however this change causes some duplicate natural accidentals.
Minimal reproducing sample:

Musescore:

sample:
test_accidental_natural_repeat.zip

There's even a "double natural" in Dichterliebe measure 9:

So I suspect this is rather a workaround or in any case not taking all variables into account.
In this case it seems like your change works for extra accidentals/naturals in C major key signature but not in other key signatures like D major.

The accidental display code is clearly not optimal in OSMD and there are other issues e.g. with courtesy accidentals, and I've had a quick look before, but it looks like the accidental code needs a slightly more holistic fix.

ps: please attach your samples zipped, if relevant, e.g. the sample you showed above. otherwise everyone who wants to reproduce your result needs to reproduce the MusicXML sample first.

[chbauman]

Thanks for reviewing, it is still not working. I will have a closer look into it.