Big refactor of lib/WikiUser.php. The login mechanism no longer uses

Big refactor of lib/WikiUser.php.  The login mechanism no longer uses
HTTP authentication.  Yeay!!!!

Downsides:
  I probably broke a bunch of things.  I will fix them.  (But let me know
  when you find them.)  This is still work in progress.

  As things stand, you need cookie support in your browser to
  be able to log in.  That's fixable too (by putting session ID in
  all our URL's when neccesary.)

git-svn-id: svn://svn.code.sf.net/p/phpwiki/code/trunk@1349 96ab9672-09ca-45d6-a79d-3d69d39ca109