Expand biblatex style file.

* font-latex.el: Update copyright years, there have been
non-trivial changes in 2010, and 2011.
(font-latex-built-in-keyword-classes): Fontify Biblatex
multicites macros up to three mandatory arguments.

* style/biblatex.el (LaTeX-biblatex-entrytype): New variable.
(LaTeX-biblatex-executebibliographyoptions-options): New
variable.
(LaTeX-biblatex-language-list): New variable.
(LaTeX-arg-biblatex-cites): New function.
("biblatex"): Always set `LaTeX-using-Biber'.  Add citation
macros.
(LaTeX-biblatex-package-options-list): Move preamble options to
`LaTeX-biblatex-executebibliographyoptions-options'.