This makes it easier to add substitutions to man pages,
avoiding the separate transformation step.
mkdir -p's are removed from the rule, because xsltproc will
will create directories on it's own.
All in all, two or three forks per man page are avoided,
which should make things marginally faster.
Unfortunately python parsers must too be tweaked to handle
entities. This isn't particularly easy: with lxml a custom
Resolver can be used, but the stdlib etree doesn't support
external entities *at all*. So when running without lxml,
the entities are just removed. Right now it doesn't matter,
since the entities are not indexed anyway. But I intend to
add indexing of filenames in the near future, and then the
index generated without lxml might be missing a few lines.
Oh well.
man rules were repeating the same information in too many places,
which was error prone. Those rules can be easily generated from .xml
files. For efficiency and because python is not a required dependency,
Makefile-man.am is only regenerated when requested with
make update-man-list
If no metadata in man/*.xml changed, this file should not change. So
only when a new man page or a new alias is added, this file should
show up in 'git diff'. The change should then be committed.
If the support for building from git without python was dropped, we
could drop Makefile-man.am from version control. This would also
increase the partial build time (since more stuff would be rebuild
whenever sources in man/*.xml would be modified), so it would probably
wouldn't be worth it.
