add todos and improve db schema

Models/KanbanCard.php

@@ -458,6 +458,4 @@ class KanbanCard implements \JsonSerializable
 
         return $card;
     }
-
-    /* todo: maybe allow ref to be an object and datamapper creates that object? how does the datamapper know what kind of datamapper to use? Just assume it's called ObjectMapper? bad isn't it?! */
 }

Theme/Backend/kanban-board.tpl.php

@@ -1,8 +1,12 @@
 <?php declare(strict_types=1);
 $board = $this->getData('board');
 $columns = $board->getColumns();
-// todo: column width should be % but with min-width and on small screens full width
 ?>
+<!--
+@todo Orange-Management/Modules#197
+    Columns width should be in % but with min-width and on smaller screens full width
+    The amount of columns depends on the user settings
+-->
 <div class="row">
     <?php $i = 0; foreach ($columns as $column) : $i++; $cards = $column->getCards(); ?>
     <div id="kanban-column-<?= $this->printHtml($i); ?>" class="col-xs-12 col-sm-3" draggable="true">