Deferred initialisation of $wgIP, because it's potentially slow, especially if and...

Deferred initialisation of $wgIP, because it's potentially slow, especially if and when we add the 200 NTL proxies to the trusted XFF list. I was hoping to avoid initialisation altogether for anonymous page views, but that turns out to be difficult because of user_newtalk. It is, however, avoided for action=raw. Tested page view, newtalk, IP registration in history and recentchanges, IP block, autoblock and Special:Version.

Also moved the old proxy scan code from EditPage.php to a more appropriate location in ProxyTools.php.