Fix translatable texts: "bar line(s)" to "barline(s)"

[Jojo-Schmitz]

No description provided.

[bkunda]

@cbjeukendrup I'd be satisfied if we used "barline(s)" instead of "bar line(s)".
Certainly, there is a bit of variety out there (Oxford even uses "bar-line"!), so all we can aim for is consistency throughout the app.

[Jojo-Schmitz]

Yes, this change is just for consistency, matching other occurrences of the same term.
If we'd decide to use "bar line(s)" or "bar-line(s)", we should do it all the way, but a long time ago it was decided to go for "barline(s)"

[bkunda]

I am happy with "barline(s)"