Allow reference of existing context
...without creating a new part
Support shortInstrumentName
Support for staff groups
Continue restructure
Avoid doubled looping
More restructuring
Support group name
Support for nested groups
Support of more staff types
Avoid double barlines
Fix multiclef regression
Preparing for non-default part-group symbols
Merge pull request #487 from PeterBjuhr/musicxml

Musicxml Export wip