Merge pull request #54 from oreillymedia/htmlbook-xsl

First Pass at EPUB generation now complete
Merge pull request #55 from oreillymedia/htmlbook-xsl

Support for specifying TOC section depth
Merge pull request #56 from oreillymedia/htmlbook-xsl

Refactoring and minor improvements
Tweak to schema import for XML namespace to make xmllint happier.
Merge pull request #57 from oreillymedia/xmlschema

Tweak to schema import for XML namespace to make xmllint happier.
Merge pull request #58 from oreillymedia/htmlbook-xsl

Bug fixes for handling of localization parameters
Fixed bug in handling of $embedded.fonts.list param that required there to be a newline at end of the list.