Improvement to the MessageBoxes

[amirmasoudabdol]

I noticed this not so professional message, "There are unapplied changes to your filter; what would you like to do?", and while looking into that, I ended up improving the message box a bit. Because of macOS Guidelines, Qt cannot set the TitleBar text on macOS, and that makes the dialog looks a bit too bold. I don't expect this to break anything on Windows, but it's good to check it anyway.

@boutinb, I have changed a few labels and text, do I have to do anything for this to get into our translation portal?

[AlexanderLyNL]

To me the "Would you" construction works, but if prefer what microsoft does, then that's fine as well.

[amirmasoudabdol]

Let's go with the "Would you" then!

[amirmasoudabdol]

@boutinb I see that to fix this properly, I need to change a few strings, and as you said this might make it tricky for the translators. I think I continue working on it, but we merge it after 0.16.1 that there is enough time for the translators to catch up. Is that a good idea?

[boutinb]

Yes there is no need to implement this in 0.16.1

[JorisGoosen]

Ok I rebased and updated the code to the current JASP version. But Im having trouble pushing to this branch. So Ill open a new PR.