add support for python 3 to genshi.filters: * minor changes to track encoding=None API change in core genshi modules. * renamed genshi/filters/tests/html.py to test_html.py to avoid clashes with Python 3 top-level html module when running tests subset. * did not rename genshi/filters/html.py. * i18n filters: * ugettext and friends are gone in Python 3 (and only gettext and friends exist and they now handle unicode) * Some \ line continuations inside doctests confused 2to3 and so were removed them. * Testing picked up a problem (already present in trunk) where Translator.__call__ could end up defining gettext as an endlessly recursive function. Noted with a TODO.