"New" Wiki verb

Changes client/verb/wiki() to be more useful.
You can now type 'wiki [query]' to look something up quickly.  For example, 'wiki cult' brings up the cult guide in your web browser.

The wiki button on the top right will also do this, but it will ask you for the thing you want.  If you input nothing, it brings you to the front page.

It uses wikiurl, so other servers should be compilable, if they change their wikiurl.