4.9 Build system
We currently use make and stepmake, which is complicated and only
used by us.  Hopefully this will change in the future.
Version-specific texinfo macros
- 
made with 
scripts/build/create-version-itexi.py and
scripts/build/create-weblinks-itexi.py
 - 
used extensively in the 
WEBSITE_ONLY_BUILD version of the
website (made with ‘website.make’, used on lilypond.org)
 - 
not (?) used in the main docs?
 - 
the numbers in VERSION file: MINOR_VERSION should be 1 more than
the last release, VERSION_DEVEL should be the last online
release.  Yes, VERSION_DEVEL is less than VERSION.