I don't have enough knowledge for a LGTM, but reading the source code I
noticed one detail...
https://codereview.appspot.com/256230045/diff/1/lily/performance.cc
File lily/performance.cc (right):
https://codereview.appspot.com/256230045/diff/1/lily/performance.cc#newcode92
lily/performance.cc:9
Reviewers: ,
Message:
This patch adds support for setting the MIDI sequence name for MIDI
output files using the value of the "midititle" field from a relevant
\header block, and falling back to using the "title" field if
"midititle"
has not been defined. (This should be analogous to how "pdftit