Add newline support for printing

[Brambor]

I would like to line break / newline when editing the sheet before specific measures. It must be reflected in printing. It is almost useless otherwise. Example: I would add linebreaks at red lines for easier reading. The result would look like this, only much prettier:

Additional Context I googled this: https://www.google.com/search?q=tux+guitar+newline&oq=tux+guitar+newline

And found many similar requests: https://music.stackexchange.com/questions/105210/line-breaks-or-page-formatting-in-tuxguitar https://sourceforge.net/p/tuxguitar/feature-requests/77/ https://www.reddit.com/r/Guitar/comments/85jspg/question_anyone_here_use_the_software_tuxguitar/ https://www.banjohangout.org/archive/303197

[guiv42]

analysis of feasibility on-going. Adding the possibility to insert linefeed is quite easy. The most complex question is how to handle the evolution of ".tg" file format (new data to be encoded in the file), and eventual compatibility with previous versions of TuxGuitar.

[guiv42]

Feasibility confirmed. However it will not be integrated directly in next version (1.6.2), but most probably in the following one. See this discussion, the difficult part is to handle properly the evolution of file format. Functionally, feature is implemented in tuxguitar-next branch, with a dedicated checkable item in "Measure" menu. But presence of line feed in measures is not stored into tablature file.

[guiv42]

"newline" feature is now fully implemented in tuxguitar-next branch. Pre-release is available. Warning: for test only. Take care, new file format is not fully stabilized. Files saved with app from tuxguitar-next branch cannot be opened by other versions of TuxGuitar, and we cannot guarantee they will be readable by next versions even in this branch.