replace all mb_* calls with their non multibyte version, fixes #398

lib/models/SimpleCollection.class.php

@@ -688,7 +688,7 @@ class SimpleCollection extends StudipArrayObject
                     $value2 = static::translitLatin1(mb_substr($d2[$field], 0, 100));
                 }
                 $ret = $sort_func($value1, $value2);
-                if (mb_strtolower($dir) == 'desc') $ret = $ret * -1;
+                if (strtolower($dir) == 'desc') $ret = $ret * -1;
             } while ($ret === 0 && next($sorter));
 
             return $ret;

lib/models/SimpleORMapCollection.class.php

@@ -110,8 +110,8 @@ class SimpleORMapCollection extends SimpleCollection
      */
     public function setClassName($class_name)
     {
-        $this->relation_options['class_name'] = mb_strtolower($class_name);
-        $this->deleted->relation_options['class_name'] = mb_strtolower($class_name);
+        $this->relation_options['class_name'] = strtolower($class_name);
+        $this->deleted->relation_options['class_name'] = strtolower($class_name);
     }
 
     /**
@@ -131,7 +131,7 @@ class SimpleORMapCollection extends SimpleCollection
      */
     public function getClassName()
     {
-        return mb_strtolower($this->relation_options['class_name']);
+        return strtolower($this->relation_options['class_name']);
     }
 
     /**
@@ -236,4 +236,4 @@ class SimpleORMapCollection extends SimpleCollection
         }
         $this->storage = array_values($this->storage);
     }
-}
+}
\ No newline at end of file