#6 Characters not unaccented

[Robert Kaye]

The ISO 8859-1 characters 216 (&Oslash) does not get
unaccented to O.

Also, the characters 198 and 230 (Æ, æ) do
not get unaccented to Ae and ae. I'm not sure if
unaccent is supposed to unaccent from one character to
two, but I figured I'd mention it.

Thanks for the great module!