Cache revision lookups done by Parser

Cache revision lookups done by Parser

Inverse flame graphs shows revision lookups as one of the
big three queries (Revision, LinkCache, getTitleInfo of
ResourceLoaderWikiModule).

This works via a new Revision::newKnownCurrent() method
needs both page/rev ID from the DB (to avoid invalidation)
and fetches the user name and rev_deleted if needed (again
to avoid invalidation). Parser does not care about fields
anyway in the template path.

Also improved cross-wiki support a bit, and fixed up some
docs and IDEA errors.

Change-Id: Icad602dba5de18c7758b77fd23b0a450ff21d09f