ODD to XHTML transformation doesn't generate links where the Guidelines has them

[martindholmes]

The default ODD to XHTML transformation, as provided by Oxygen, creates a single-file HTML output which resembles the TEI Guidelines in many ways, but in one important respect it is different: in specification tables, the elements listed in the "contained by" and "may contain" cells are not linked to their own specification tables. This makes navigating the documentation a bit annoying; you can only get to the spec table for an element by hacking the URL (or from an explicit link created from a <gi> element in the prose section).