Fix semester switcher

~dev_rating/application/classes/Controller/Handler/Settings.php

@@ -81,9 +81,11 @@ class Controller_Handler_Settings extends Controller_Handler
     }
 
     public function action_setSemesterID() {
-        $semester = $this->post['semesterID'];
-        if (is_int($semester) && $semester > 0) {
-            $this->user->SemesterID = $semester;
+        $this->post
+            ->rule('semesterID', 'not_empty')
+            ->rule('semesterID', 'digit');
+        if ($this->post->check()) {
+            $this->user->SemesterID = (int) $this->post['semesterID'];
         }
     }
 }