Revert broken rewrite of login forms:

r55990 "* Totally refactor includes/specials/SpecialUserlogin.php:"
r55991 "Followup to r55990 - Remove debugging hack :("
r55994 "Followup to r55990 - rename method to avoid PHP Strict warnings"
r55997 "Follow-up to r55990, per comments:"

Continued reports of breakage with the new version...
Non-vital changes of this magnitude should probably be worked up on a branch to ensure everything's consistent before pushing them to trunk.