OrderPanel improved

[max]

Orderpanel update.
* added support for payments ID stored in customer_id (usefull for payment checking)
* added support for html attachments in order emails (custom template supported)

checkout.php > affected row 96 > set order id as customer id
reseller-functions.php > affected row 1625 > setup new constant {SYMBOL} as identifier in payments
reseller-functions.php > affected row 1610 > if isn't domain set the subdomain name in language locations
reseller-functions.php > affected row 1532-1534, 1664-1672 > Attachment with order details supported. It's can be enabled or not