Added handling for $html4.structural.elements parameter that lets you toggle on/off whether to convert <section>/<figure> to <div> for HTML4 compatibility.
Fix typo in predicate.
Fixing typos in attribute value specifications.
Special handling for figure, if converting to <div> for backward compatibility.
Renaming idgen.xsl to elements.xsl, to reflect usage as all-purpose element postprocessor.
Handling for figcaption in HTML4 compatibility mode.
Removing inaccurate comment.
Merge pull request #61 from oreillymedia/htmlbook-xsl

Parameterized support for HTML4 compatibility