Merge pull request #68 from oreillymedia/htmlbook-xsl

CSS <link> handling for chunked output and tweak to EPUB metadata handling
Merge pull request #71 from oreillymedia/htmlbook-xsl

Removing variables from xsl:key "use" attributes in indexgen.xsl
Support for adding <math> or <svg> elements in inline contexts whenever possible (exceptions for where it would result in a nondeterminist content model.
Adding support for <math> and <svg> in a few more inline contexts where it is feasible.
Merge pull request #72 from oreillymedia/xmlschema

Support for adding <math> or <svg> elements in inline contexts whenever possible
Updated spec for footnotes.
Merge pull request #73 from oreillymedia/xmlschema

Updated spec for footnotes
Footnote handling for one-chunk output (i.e., output not using chunk.xsl)
Merge branch 'master' of github.com:oreillymedia/HTMLBook into xmlschema
Footnote handling for chunked output.
Setting default param values for process.footnotes.
Need a space between footnote marker and footnote text.
Merge pull request #74 from oreillymedia/xmlschema

Footnote handling!!!
Footnoteref handling.
Only do footnoteref processing if process.footnotes is enabled.