lilypond-book: Rewrite processing of snippets (issue 555220043 by address@hidden)

[nine . fierce . ballads]

LGTM, but I'm no guru.


https://codereview.appspot.com/555220043/diff/553480046/scripts/lilypond-book.py
File scripts/lilypond-book.py (right):

https://codereview.appspot.com/555220043/diff/553480046/scripts/lilypond-book.py#newcode432
scripts/lilypond-book.py:432: snippet_names_file = 'snippet-names-%s.ly'
% checksum
It's strange that this is named *.ly but does not contain ly code. 
That's not your problem, though.

https://codereview.appspot.com/555220043/diff/553480046/scripts/lilypond-book.py#newcode481
scripts/lilypond-book.py:481: # Sort the keys / basenames to get a
stable order.
Good idea.  Is there a reason you chose not to build sorting into
process_snippets()?

https://codereview.appspot.com/555220043/