NavigationItem: Add property priority

refs #5600

library/Icinga/Web/Navigation/NavigationItem.php

@@ -31,6 +31,15 @@ class NavigationItem implements Countable, IteratorAggregate
      */
     protected $active;
 
+    /**
+     * This item's priority
+     *
+     * The priority defines when the item is rendered in relation to its parent's childs.
+     *
+     * @var int
+     */
+    protected $priority;
+
     /**
      * The attributes of this item's element
      *
@@ -165,6 +174,29 @@ class NavigationItem implements Countable, IteratorAggregate
         return $this;
     }
 
+    /**
+     * Return this item's priority
+     *
+     * @return  int
+     */
+    public function getPriority()
+    {
+        return $this->priority;
+    }
+
+    /**
+     * Set this item's priority
+     *
+     * @param   int     $priority
+     *
+     * @return  $this
+     */
+    public function setPriority($priority)
+    {
+        $this->priority = (int) $priority;
+        return $this;
+    }
+
     /**
      * Return the value of the given element attribute
      *