Automatically use the new password_hash function if php version is 5.5 or higher, which is more secure than crypt and avoids warnings in PHP 5.6 for empty salt in crypt.
If you are running PHP 5.5 or higher, run the misc/testing/dev/find_password_hash_cost.php script and set the number it gives in settings.php nZEDb_PASSWORD_HASH_COST to make the password algorithm stronger.