Stage 2 of war on $wgTitle!! Make OutputPage, Skin and children rely on mTitle rather...

Stage 2 of war on $wgTitle!! Make OutputPage, Skin and children rely on mTitle rather than $wgTitle. In theory, you could have an OutputPage/Skin that was referring to some title other than $wgTitle, unlikely though. In any case, make getTitle() return $wgTitle for now, just in case.