Version 2.1.0

Hi Prestashop Team,

here is the latest Version for the module.
New Features:
- Refund within the Prestashop administration(Orderdetails)
- Preauthorization / Capture
 * Create a preauth instead of an Transaction and charge the customer later(Orderdetails)
- Added compatibility to EU-Legal module
- Added Upgrade script

best regards,
Stefan
$order_id has already been escaped with the [(int) line 32](https://github.com/PrestaShop/pigmbhpaymill/pull/16/files#diff-d856bc138af648fa0f7a949c3ecbc51cR32).