[MusicXML] Support breaks in secondary beams (import and export)
Currently MuseScore's MusicXML engine ignores breaks in secondary beams -- both when importing MusicXML and when exporting to MusicXML.
Here's example data for you. I created the following notation in Finale:
The attached MusicXML file musicxml_broken_secbeams.xml was generated by Finale with the latest Dolet plugin. When I import this in MuseScore 2.0.2, the beam breaks are ignored:
The attached MuseScore file musicxml_broken_secbeams.mscz has broken secondary beams. When I export it to MusicXML using MuseScore, the secondary beams are no longer broken in the resulting MusicXML file (musicxml_broken_secbeams_musescore.xml).