* XSLT stylesheet included from other stylesheet are not among dependencies
  (if you modify html.common.xsl) then the html output won't be rebuilt

* Support for man pages

* Support for embedded css stylesheets in generated HTML documents

* There is an issue with .d files, they are not sometimes regenerated when
  one of the files included gets changed to a non-existent file and back
  (maybe it happens only when you run make clean html)