Fix globals and deprecated methods used in SpecialPages

* Add new WantedPropertiesPageTest coverage: 100% CRAP: 8

* wfViewPrevNext was deprecated in MW 1.19 and breaks tests
* Linker::makeLinkObj warnings since 1.21 breaks tests

Change-Id: If15d224bed533b4a5fa96433a3a36b568772f463