Better management of package options.

* latex.el (LaTeX-provided-class-options): New buffer-local
 variable. (LaTeX-provided-class-options-member): New
 function. (LaTeX-provided-package-options): New
 buffer-local variable.
 (LaTeX-provided-package-options-member): New function
 (LaTeX-auto-cleanup): Rewrite to support
 `LaTeX-provided-{class,package}-options' variables.
 (LaTeX-arg-usepackage): Ditto.

* tex.el (TeX-auto-store): Write to parsed file values of
`LaTeX-provided-{class,package}-options' variables.
(TeX-auto-insert): Fix indentation of inserted lines.
(TeX-search-files-by-type): Fix typo in doc-string.
(TeX-add-to-alist): New function.
(TeX-quote-language-alist): Fix typo in doc-string.

* style/babel.el (LaTeX-babel-package-options): Add missing
languages.
(LaTeX-babel-package-options): Add options other than
languages.
(LaTeX-babel-active-languages): Use
`LaTeX-provided-{class,package}-options'.  Loop over actually
used options instead of all babel languages.
("babel"): Run styles of active languages.

* style/biblatex.el ("biblatex"): Use
`LaTeX-provided-package-options-member'.
(LaTeX-biblatex-package-options): Consider the `ask' value for
'TeX-arg-input-file-search'.

* style/kpfonts.el ("kpfonts"): Use
`LaTeX-provided-package-options-member'.

* style/siunitx.el: Rename `TeX-siunitx-*' functions to
`LaTeX-siunitx-*' for consistency.
("siunitx"): Use `LaTeX-provided-package-options-member'.
Minor fix for the latest commit.