1. Add a new knob, GEN_INDEX. If defined (nothing does yet), collateindex.pl

will be run to generate index.sgml, an automatically generated index for
the document. This is also added to the list of dependencies.

2. Add a DOCBOOKSUFFIX variable, defaulting to "sgml", so we can write
   
   MASTERDOC?= ${.CURDIR}/${DOC}.${DOCBOOKSUFFIX}

Requested by: Michael Wiedmann <mw@miwie.in-berlin.de>

Linux Documentation Project

3. Set the DSSSL 'openjade' variable to #t if we're processing with OpenJade.

4. Work around a bug in the stylesheets. If we split the <legalnotice> out in to a separate file it isn't added to the HTML.manifest. Check for it by hand, and include it if necessary.