(bug 28242) Make url's of the form http://mediawiki.org/wiki/w:Somewhere_on_pedia...

(bug 28242) Make url's of the form mediawiki.org/wiki/w:Somewhere_on_pedia give a 301 (permenant) redirect instead of a 302.

This is to make google when indexing a page like http://mediawiki.org/wiki/w:Somewhere_on_pedia to report its target, not the
original url as the url of the page. This only affects urls where the (local) interwiki target is directly in the url.
Pages that contain #Redirect[[w:Somewhere_on_pedia]] will still use 302 (Temporary) redirects since such pages are by
no means permenantly redirected.

Also clarify docs on $wgDisableHardRedirects since the setting confused me.

See also google's spiel on 301 redirects http://www.google.com/support/webmasters/bin/answer.py?answer=93633