- Add Japanese customization
- Like in XHTML, do not generate outer links in TOC entries since
  TOC entries themselves are cross-refereces, so move a customization to
  the common part.
- Enable FOP extensions, which eliminate most of the warnings and turn on
  some advanced features, like PDF bookmarks.
- Allow breaking lines of verbatim elements at spaces.  Such a break is
  denoted with a special arrow symbol.  This technique is commonly used
  in technical books to present long source lines.
- Use other monospace font, that has an appropriate arrow symbol for this.
- Add some padding to verbatim environments.
- Variablelists look better as blocks
- Add some negative tracking to inline monospace text so that it fits
  better the body text
- Improve padding of verbatim blocks
- Adjust list spacing
- Rename the titlepage specs to reflect that they are used for XHTML
- Factor out parts that are reusable for FO output
- Add FO titlepage customization
- verbatim hyphenation requires higher recursion depth
- Use the xetex backend since it works better for Unicode
- textobjects do not work and we do not need them anyway
- Somehow hyphenation path handling is buggy but it works when set in the
  base path
- Add dblatex customization for Japanese
- Readjust margins so that page numbers are more separated and thus are
  more visible
- Stick captions where they belong
- Highlight examples with a bolder and a title-like caption
- Render blue links by default.
- Add support for a single variable that indicated whether we are building
  for screen or for print.  In the latter case, blue links are disabled
  and the URI of links is included in a footnote.