Hopefully slightly saner handling of character entities in links; now will

Hopefully slightly saner handling of character entities in links; now will
use UTF-8 characters on a UTF-8 wiki for the Latin-1 named entities; this
prevents corrupt in-wiki links for cases such as [[Weiß kreuz]] or
[[Brûker:Foo]]. There is a small chance this will harm interwiki
links to latin-1 wikis that don't accept UTF-8 incoming URLs, but on
balance this is a lesser harm. Raw bytes in such links can still be used
(%XX) if need be.

This shouldn't change behavior on Latin-1 wikis.