Removed link from header

I'm not sure why I made "El Wiki" a link to /wiki/ in the first place,
so I'm removing the link.
Added creole link resolver

Function for resolving bare links when rendering creole.  A bare link
is one that (presumably) names a page: [[example]] or [[link|text]].

See also the docstring for `creole-link-resolver-fn'.
Fixed typo