xslt.py whould return the result as a string

[Sam Ruby]

Eric van der Vlist wrote:
> 
> The current version of xslt.py doesn't seem to support the case when its
> "output_file" argument is None. In that case, other shell script such as
> py.py return the result while xslt.py just returns nothing and that
> breaks the pipe when xslt.py is used to run a filter.

That's just unacceptable.  :-)

OK, I've added a test for running xslt as a filter, and got it working 
with Python 2.2, Python 2.4, and Python 2.5, with either libxslt2 or 
xsltproc installed.

You know the drill: 'bzr pull'.

- Sam Ruby