(also handy info for using with the git difftool)
- http://superuser.com/questions/79920/how-can-i-diff-two-xml-files
- http://www.w3.org/TR/xml-c14n
- https://groups.google.com/d/msg/git-users/Wou2d9ovZPo/1CHY9VxNAdgJ
- http://www.manageability.org/blog/stuff/open-source-xml-diff-in-java/view
- http://useless-factor.blogspot.com/2008/01/matching-diffing-and-merging-xml.html