Changes in 3.1:
* html/teihtml-struct, common/teicommon.xsl: move handling of
cross-referenced headers to common
* makeURL to makeHyperLink, and be common
* revised structure to separate out fo, latex, common, html
teixsl-fo is a set of XSLT specifications to transform TEI XML
documents to XSL Formatting Objects. It concentrates on TEI Lite, but
adding support for other modules is fairly easy.