Add example.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Add TODO.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Add `bibeltex-latex-bibliography-format'.

This allows more flexible bibliography formatting, e.g., biblatex
support, when `bibeltex-use-bibtex-in-latex' is non-nil.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>