Sanity updates.

- Rename account.php to profile.php.
- Rename contacts.php to users.php. Leave old versions around to redirect.
- Fax technology is slightly obsolete.

- Use DocumentHelper to download documents.
- Use DocumentHelper to create zip files.

- Split mailtemplate.inc into mailer.php (code) and mailtemplate.inc (text).

- The .htaccess mod_rewrite can handle slash URLs with multiple
  components, thanks to regex backreferences (shakes fist).

I am sick of maintaining multiple independent versions of this code,
so am trying to abstract stuff out and stabilize on the best versions
of my decisions.