Extremely large commit:

- Fixed tiny quote problem in account.php.

- Fixed tiny bug in comment.inc.

- Fixed tiny bug in comment.module.

- Fixed tiny bug in meta.module.

- Simplified user_access() API.

- Rewrote link system: still needs fine-tuning and testing so don't
  upgrade if you are running a production site. ;)

  Updated all modules and themes to reflect this change.  All other
  themes and modules need updating too!