DB schema change.

DB schema change.

In CentralAuth (and related changes interface changes in Newuserlog and the core):

* Moved the AutoAuthenticate hook to User::loadFromSession(), to defer processing for longer and avoid unstub loops
* Undeprecated User::setID()
* Added partial support for new user log registration and IP-based blocking of automatically created accounts. Still needs the same support implemented in Special:Userlogin.
* Fixed all inappropriate uses of the term "DB name", changing them to "wiki" or "wiki ID". Renamed the relevant database fields.
* Refactored central session and cache support