Use unicode internally
Update xmlns attribute for XMvn config files
Pretty-print Artifact XML output
Provide unicode as well as str representation of Artifact
Port unittests to support Python 2.6
Migrate to lxml module for better support

Python 2.6 ElementTree can not properly handle namespaces at all
Fix disabling of effective POMs
Improve creating index file by config editor
Add missing brackets in comments/doc snippets