bdiff: include util.h
Without this, IS_PY3K isn't define and the preprocessor uses the
incorrect module loading code, causing the module fail to load at
run-time.
After this patch, all our C extensions (except for watchman's) appear
to import correctly in Python 3!
Mercurial's documentation is kept in reStructuredText format, which is
a simple plain text format that's easy to read and edit:
http://docutils.sourceforge.net/rst.html
It's also convertible to a variety of other formats including standard
UNIX man page format and HTML. You'll need to install Docutils:
http://docutils.sourceforge.net/
Use the Makefile in this directory to generate the man and HTML pages.