Update woocommerce-add-extra-charges-option-to-payment-gateways.php

Found this plugin for WooCommerce to add extra cost based on the selected Gateway and modified it to compensate the fees PayPal charges.
Changes are made at three locations:
1. added an extra option in the select-tag,
2. parse the 'woocommerce_???_extra_charges' in case the compensate-option was selected and calculate a new total to pay by the customer so that the shopkeeper will receive the original total,
3. removed the percentage character in the extra row that is added in the cart because I modified that row to show the exact amount that was added.