Updated mediawiki/extensions
Project: mediawiki/extensions/Wikibase  d482d9dda6d8fe74fc2a3cc2467de8ed3c9fc864

Namespace cleanup

Initial goal: Change references to aliases such as Wikibase\EntityId to their new FQN

Which forced doing: Move classes into Wikibase\Lib\Store to enable
moving away from deprecated class aliases. The updating of references
this caused is the bulk of this commit.

Along the way, this cleanup was also done

* Update refs from SimpleSiteLink to SiteLink
* Decreased visibility of several fields and methods
* Removed a pile clutter docs
* Migrated some highly deprecated code that will break with DM 1.0

Change-Id: I908c43505c3ef66386b123c01cdc40bcba9ef9b8