New features in 2.20 since 2.18
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+ • The music function ‘\\unfoldRepeats’ can now take an optional
+ argument-list specifying which type(s) of repeated music should be
+ unfolded. Possible entries are ‘percent’, ‘tremolo’, ‘volta’. If
+ the optional argument-list is unspecified, ‘repeated-music’ will be
+ used, unfolding all.
+
• A new ‘output-attributes’ grob property is now used for svg output
instead of the ‘id’ grob property. It allows multiple attributes
to be defined as an association list. For example, ‘#'((id . 123)