* outline.el (outline-regexp, outline-heading-end-regexp): Use

* outline.el (outline-regexp, outline-heading-end-regexp): Use
variables, not options (bug#13731).

Setting this as a global option is likely to be useless, because it is
unlikely that all outline file will use the modified regexp.

Additionnally, if one of these variables if set through customize and
the outline keybindings don't work in a standard outline file, it is
hard to know why.

Thanks to T. V. Raman for reporting this.