To Do
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* Allow embedding of xvcs:id in documents, and use xvcs:id for first match pass
* Allow option to use xvcs:id instead of XPath as node identifier
* Add DTD & XML-Schema support to improve Diffs
* Add Entity Tag Versioning
* Add atomic patch, allowing individual items from the Diffgram to be applied
* Add capability to reverse diffgram
* Do LCS diff on large text nodes to reduce diffgram