Fix #9873: MU does not taken file name from title when saving score

[HemantAntony]

Resolves: #9873

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[DmitryArefiev]

I tested #9873 (comment) briefly on Win/Mac and it looks fine, but it also should be reviewed.

@cbjeukendrup Can you help with CR please?

[HemantAntony]

@cbjeukendrup Can you review this? :)

[cbjeukendrup]

I think it's fine to call simplified first, and to remove fn = fn.replace('\n', '_');. Otherwise, newlines will be converted into _ even if removeSpace is false, while it would be much more logical to convert newlines to spaces in that case.

[cbjeukendrup]

To be honest, I'm not a great fan of comparing strings that may have been translated (we've seen this causing trouble a few times in the past). But in this case I don't see a much better solution, and it seems harmless enough.

But I wondered one thing: shouldn't we look at the title specified in score properties first, before we resort to looking in the notation itself?