=== New features in 1.18 ===
* BREAKING CHANGE: action=watch / action=unwatch now requires a token.
-* BREAKING CHANGE: Article class heirarchy split into WikiPage (backend).
+* BREAKING CHANGE: Article class hierarchy split into WikiPage (backend).
and Article (frontend) hierarchies. Several hooks now pass a WikiPage object instead
of an Article object. These hooks all use an $article paramater as documented in hooks.txt.
Extensions should be updated to account for this, though most won't require any changes.