Also switch to Times New Roman for the main text. The music is set
with Postscript Times, so this is the easy approach to better typographic
consistency.
Add a list of tune first lines to the Booke. First, a small Python script to
filter a .abc file and spit out just enough to give a graphic of the first line
without the title. Then generate these graphics and generate a new section in the Booke
with a longtable of tune name and the first line graphic.
Switched to A5 portrait. In landscape it stretches the image to fit the
width, and that causes a lot of longer tunes to become too high to fit
properly on the page.
Build the book in a separate build directory. The build generates lots
of .abc files and so forth, which it is convenient to have elsewhere
so you can ignore them. I did experimend with \abcinclude, but that has
a lot of expectations about the files being in the current directory.
If a tune has multiple titles, pick the first.
Adjust abcm2ps options to preserve the line breaks in the ABC.