code: private function replaceUtf8(&$original, $replacement, $position)
  	{
  		$start = mb_substr($original, 0, $position, "UTF-8");
  
  		$end = mb_substr($original, $position + 1, mb_strlen($original, 'UTF-8'), "UTF-8");
  
  		$original = $start . $replacement . $end;
  	}
docs: Replace a character in a given position of a string.
  
  @author	Andrea Marco Sartori
  @param	string	$original
  @param	string	$replacement
  @param	integer	$position
  @return	void