TODO

README
- Full Documentation
- ?
Code
- More in-code documentation, doc blocks, etc.
- More validation, more defensive programming
- Validate content being xhtml
Tests
- Just create more
Planned Features
- Cover image
- Custom additional content
- ?
Changes
- dcterms:modified should be filled in automatically, as it is supposed to be the "last edited" date of the epub file itself. The optional dc:date is for the "(original) publication date".