- Improve the `set` support: dblatex can build all the PDF files (one per book) and the xr-hyper package is used to make cross-references between books.

- Improve the XeTeX font switch macros (still experimental).

- Add some hook to external error handlers.

- Change the verbatim implementation in order to be able to easily add new elements embeddable in `programlisting`s.

- Add the parameters:

  - `glossary.tocdepth`.

  - `glossary.numbered`.

  - `refclass.suppress`.

  - `use.id.as.filename`.

- Fix some bugs.