Blame hashar for this giant commit; he teased me for making so many smaller ones...

Blame hashar for this giant commit; he teased me for making so many smaller ones earlier... :D
* Internalise $mAddress/$mUser, $mBy/$mByName, $mEnableAutoblock, $mId as getTarget(), getBlockers(), isAutoblocking(), getId().
* This required editing AbuseFilter and CheckUser backwards-incompatibly, so push the rest of the changes out to those extensions.
* Attack the evil 14-parameter constructor and gratuitously-confusing newFromDB( $notVeryImportantParameter, $moreImportantParameter)
* Reimplement the hack for bug 13611 in a slightly less fragile fashion; could still do with further cleanup, but then again the login frontend is its own can of worms... :S
* Remove transitionary getTargetAndType() and newFromTargetAndType() methods
* Some optimisation in parseTarget()
* Fix the broken phpunit test mentioned in r84251