Escape markdown code in column tooltips.

This is needed to avoid issues when the code contains quotes.

app/Template/layout.php

@@ -37,7 +37,7 @@
             <nav>
                 <h1><?= $this->a('K<span>B</span>', 'app', 'index', array(), false, 'logo', t('Dashboard')).' '.$this->summary($this->e($title)) ?>
                     <?php if (! empty($description)): ?>
-                        <span class="column-tooltip" title='<?= $this->markdown($description) ?>'>
+                        <span class="column-tooltip" title='<?= $this->e($this->markdown($description)) ?>'>
                             <i class="fa fa-info-circle"></i>
                         </span>
                     <?php endif ?>