* Modified some methods of SpecialWatchlist to be non-static so that they can use...

* Modified some methods of SpecialWatchlist to be non-static so that they can use $this->getTitle() instead of having to pass the special page's name
* Use context variable instead of global ones
* Really use countItems()
* Updated InterwikiIntegration for these changes; I'm not keeping b/c since anyway that extension was broken until now because SpecialWatchlist::countItems() was static and SpecialInterwikiWatchlist::countItems() not (was throwing fatal error)