* In fast mode, diff test2.xml to test3.xml in "merged" mode:
Text-moved-here should not be used, instead deleted-text. How to detect?


* Algorithm improvement: look at the related-to lists of both nodes, to avoid
matching
	<short>Whether to print the page URL in the header</short>
	<long>Whether to print the page URL in the header</long>


* Add sub-or-superstring modification, since users are very interested in that,
and this should be possible without losing too much performance.


* Make writer a runtime choice, not a compile time


* Specify merged format closely


* Catch and handle namespace clashes - you can't run ssddiff on ssddiff
results currently!


* Put dummy nodes in XUpdate into a special namespace?