Building macOS GUI

[lilypond]

I recently downloaded the Mac version of Lilypond, unofficial 64-bit version 
from <https://bintray.com/marnen/lilypond-darwin-64>, and using the GUI, ran in 
to a few rough spots.  Overall, the system is amazing! I generated the score I 
wanted with no issues.

I set up the LilyDev environment, but the app’s source doesn’t appear to be in 
the repo it clones.  In fact the only place I see reference to the GUI app at 
all is <http://lilypond.org/website/macos-x.html>, with no source information.

Can someone point me to the source code?  And if I develop a patch, is there a 
more appropriate list to discuss it on?  Thanks!

/N