www/beginexp_form.php3 - No initial whitespace in plab Slice Description textarea.
         sql/database-fill.sql - Use default:fulltext for 'experiments','expt_name'
             to allow multi-line Slice Description in plab_ez->beginexp->batchexp.
         www/moduserinfo.php3 - Pass null string for optional usr_addr2 and notes fields.
         backend/moduserinfo.in - Null string attr comes from XML as an undef value.
         db/User.pm.in - Distinguish between undef and null string in ModUserInfo.