New hook, 'SearchResultInitFromTitle'

New hook, 'SearchResultInitFromTitle'

This hook lets you change the revision ID used for a page (a Title
object), when displaying that page in search results. It's useful for
the Approved Revs extension, so that pages whose approved revision is
not their latest can have their approved revision, not the latest one,
show up when doing a search text. It's also potentially useful for
other, similar extensions, like FlaggedRevs.

Change-Id: Ic4bad8dfaa83de131db9c8e7667d7f5767d8d5f5