Basically, the XML processing has been left untouched, with very small
tweakings (boolean instead of 1/0, python syntax, etc.). The main idea was to
separate the command line processing (xml2po.py.in -> xml2po) and the main
processing (moved as a module in /usr/lib/python??/site-packages/xml2po, with
/modes as a subdirectory). It should now be possible to call xml2po from any
python code with an "import xml2po" command, without resorting to command line.