Order emails by id to guarantee chronological order (issue #15) (?)
Create edit-account.php from register.php for editing account info (#12)

* Picture utilities common to both have been moved to utils-pic.php
* register.php will check for whether the user is logged in and, if so,
  display a message and not show any forms, but the forms themselves
  with possibly unnecessary logic haven't been touched yet (I haven't
  quite figured out how the two-part registration works)
* add two more "DEFAULT ''"s to the schema so the two-part registration
  works (given issue #9, this shouldn't be how things work, but one
  commit at a time.)
* Users can't edit their username anymore. (As far as I can tell, they
  couldn't have successfully done so originally either, because the
  password check would have failed since the username is part of the
  hash. Might as well make it explicit.)
* Misc. other organization (<h2> juggling, as usual)