Account Banking - Payments Export Infrastructure

Infrastructure to export payment orders plus some bug fixes and obvious enhancements to payment orders that will hopefully land in offical addons one day.

This technical module provides the base infrastructure to export payment orders for electronic banking. It provides the following technical features: * a new payment.mode.type model * payment.mode now has a mandatory type * a better implementation of payment_mode.suitable_bank_types() based on payment.mode.type * the "make payment" button launches a wizard depending on the payment.mode.type * a manual payment mode type is provided as an example, with a default "do nothing" wizard

To enable the use of payment order to collect money for customers, it adds a payment_order_type (payment|debit) as a basis of direct debit support (this field becomes visible when account_direct_debit is installed). Refactoring note: this field should ideally go in account_direct_debit, but account_banking_payment currently depends on it.

Bug fixes and enhancement that should land in official addons: * make the search function of the payment export wizard extensible * fix lp:1275478: allow payment of customer refunds * display the maturity date of the move lines when you are in

the wizard to select the lines to pay