$user: user that watched
$page: WikiPage object watched
+'WatchlistEditorBeforeFormRender': Before building the Special:EditWatchlist
+form, used to manipulate the list of pages or preload data based on that list.
+&$watchlistInfo: array of watchlisted pages in
+ [namespaceId => ['title1' => 1, 'title2' => 1]] format
+
'WatchlistEditorBuildRemoveLine': when building remove lines in
Special:Watchlist/edit.
&$tools: array of extra links