stringutil: support more types with pprint()
bytearray wasn't working. Integers and floats were not being
formatted.
I /think/ %f is portable across both Python 2 and 3, as it should
default to 6 decimal points on each.
Differential Revision: https://phab.mercurial-scm.org/D3302
#require docutils gettext
$ $TESTDIR/check-gendoc sv
checking for parse errors