stringutil: add function to pretty print an object
This is inspired by the pprint() module/function (which we can't
use because the output is different on Python 2 and 3 - namely the
use of b'' literals).
We hook it up to `hg debugwireproto` for printing the response to
a wire protocol command.
This foreshadows future peer work, which will support decoding
CBOR responses into rich data structures.
Differential Revision: https://phab.mercurial-scm.org/D2987
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.