Emacs lilypond-ts-mode update: editor navigation by musical moment

Hi all,

I want to share a new feature I just pushed for lilypond-ts-mode: cycle
forward/backward through  the same rhythmic position in all parts, even if
they are spread across multiple files. This is made possible by evaluating
LilyPond code within a Guile REPL using an engraver that outputs a list
mapping moments to input locations.

I'm pretty excited about this, as it's a type of editing workflow that has
been much requested over the years, and which as far as I know has not
existed before. I believe that the Scheme part of this could probably be
upstreamed into LilyPond and used by non-Emacs editors to implement a
similar feature.

Fair warning, there are probably some bugs at this stage, hence why I
haven't yet shared this on the user list. But please give it a try:
https://github.com/shevvek/lilypond-ts-mode.

Saul