Allow for 'noninteractive' reading of scores

For the batch export plugin two features would come very handy.

1. don't set the created flag when importing a score. It would be possible to close it without the user having to answer a confirmation dialog.
2. don't append the score to the recent score list.

I'd propose this:

Score* MuseScore::readScore(const QString& name, bool noninteractive = false)