Add Paypal support

This project will never provide that integration, since it is too specific and we cannot ship with support for all sorts of third party payment methods or webshops. That would make this project too hard to maintain. Instead, a separate project will have to be created that provides integration between Payment and Paypal. I will mark this issue postponed, so it will be visible in the issue queue and anyone wanting to provide this integration can link to the newly created project here.

Perhaps. It will certainly not be part of Payment itself.

See http://drupal.org/project/payment_paypal.