Sometimes it's required or at least a good option to have a cite this page
link on pages, that aren't content pages (like the project namespace).
This change adds a new configuration option for this extensions to allow to
add namespaces as namespaces that should have a cite this page link, even if
they're not a content page.
Bug: T150053
Change-Id: I2523bd9124ab8998a7c327d8045d7585d4dcf8b4
The SkinTemplateToolboxEnd hook is nasty and requires echo-ing raw HTML.
It also has the problem that if there are any other extensions using
that hook, the CiteThisPage link will easily end up in the wrong place
and under the wrong heading.
This is trivial to fix though by using the BaseTemplateToolbox hook,
which is designed for actually adding links to the toolbox!
Bug: T140290
Change-Id: I9557130c40e17edc12a225a3b7b1cdec028f93d0
