Add Python 3 support.

[xml-template] / python / attribute2.py

#! /usr/bin/python
import xmltemplate

doc = xmltemplate.process_file("../xml/clone.xml", {
        "color": "blue",
        "#things": xmltemplate.alternate("li/class", [
                { "li": "Raindrops on roses" },
                { "li": "Whiskers on kittens" },
                { "li": "Bright copper kettles" },
                { "li": "Warm, woolen mittens"},
        ], "odd", "even")
});
print(doc.toxml())