add paypal as library

There are no need to implement it in CodeIgniter itself, just use their own PHP SDK:
https://github.com/paypal/Checkout-PHP-SDK
https://developer.paypal.com/docs/checko...setup-sdk/

https://developer.paypal.com/docs/checkout/

Code:

// Just remove this line from all their example:
require __DIR__ . '/vendor/autoload.php';

// And add \ in front of all their use
use \Sample\PayPalClient;
use \PayPalCheckoutSdk\Orders\OrdersGetRequest;