Improve subscription compatibility

Added:

• Use context to generate a dedicated heidelpay logfile
• WooCommerce Subscriptions
  • Enable / Disable payment for subscription orders
  • Support for configuration
    • Change amount of subscription
    • Change date of subscription
  • Direct debit:
    • Add creditorId payment information
    • Payment info text for subscription renewal orders.

Fixed:

• Push notifications were not processed
• IFrame not working if lazyloading is active