Permit to choose Transaction Type by Payment Rules

Hello,

Thanks for this great module. just update to the new version.

Sermepa offers 14 transaction types.
We used 2 different transaction types in our website and it will be great to have an extra field for the transaction Type in the payment-rule configuration.
This way it´s easy to add multiple rules with different transaction types.

Right now, we can modify the commerce_sermepa.module in line 346
$gateway->setTransactionType('7')
and set the number of the transaction type we want. It Works perfect, but this affects to all sermepa payments so we can use just one transaction type.

I think this module can be more powerfull just adding a transaction type field.

As we need this implementation. any help will be welcome and I can help with testing (I´m sorry, I´m not a super PRO)

¿How can we use different transaction types?
- Create a new field in the configuration interface
- Duplicate the module to have different transaction tipes
-.....

Thanks for your attention and help.