Initializes the Bag
array $array:
Overrides SessionBagInterface::initialize
public function initialize(array &$flashes) {
$this->flashes =& $flashes;
// The logic: messages from the last request will be stored in new, so we move them to previous
// This request we will show what is in 'display'. What is placed into 'new' this time round will
// be moved to display next time round.
$this->flashes['display'] = array_key_exists('new', $this->flashes) ? $this->flashes['new'] : array();
$this->flashes['new'] = array();
}