Alpha 8

• MIDI files can now be exported (#55).
• Rewritten score merger, which fixes numerous issues with importing v1.7 files (#153, #154).
• The scorer polisher now correctly handles grace notes (#103).
• Grace notes are now drawn smaller and with a slash through the stem, and are no longer included in beaming patterns (#19).
• Fixed a crash when there are no available MIDI output devices (#180).
• The note duration is now preserved when changing a note to a rest (#175).
• The Increase/Decrease Duration command now updates the active note duration that is used for new notes (#70).