Add page and system breaks via command line
We should add a command line option to freeze the layout of a score by adding manual page and system breaks in places where automatic breaks occur. For example:
mscore --freeze-layout score1.mscx score2.mscz mscore --freeze-layout infile.mscx -o outfile.mscz
This is useful to enable other programs to read MuseScore files and work out where the pages and systems go without having to do expensive layout calculations. It also provides a way to "lock-in" the layout of a score before opening it in a newer version of MuseScore that uses a different layout algorithm, which would otherwise result in page and system breaks occurring in different places.
Use case: Music Braille converters need to know where page breaks occur so that they can provide print page references to facilitate blind and sighted musicians working together. High quality converters cannot depend solely on MusicXML because the specification lacks certain features necessary for Braille, hence they must use MuseScore's internal format.