Those are all found properties which seems to be "static" for one payment
service.

Follows:
  * http://www.payzen.eu/integration/document/2.2Guide_d_implementation_formulaire_paiement_V2-1-ENG-Payzen.pdf
  * http://www.payzen.eu/integration/document/Guide_technique_d_implementation_standardWebservices_Payzen_ENG.pdf
  * http://www.payzen.eu/integration/document/2.2_Guide_d_implementation_formulaire_Paiement_V2_Parametrage_Avance_Payzen_ENG.pdf

In case of reused properties use their original name.

In case of payzen properties, use thier full name with payzen_ prefix.

This fix issues when we transfer characters not allowed in xml

This is ERP5SecurePayment service which aims to provide payzen.eu integration
following ERP5SecurePayment interface.

It allows to provide various secure payment services into ERP5.

aggregate link to a Payment Transaction Group should b reset on the child accounting lines when a Payment Transaction is cloned.

Never set value when rendering! If you do, then every time writing occur and it creates conflict error which kill ERP5 scalability! To get acquisition, you just have to call __of__. Also frequent writing make data.fs very huge so quickly.

use urlsafe_b64encode as the dom_id, otherwise we need to escape many characters including periods etc.

Before this patch only coordinate_text property was editable on form, even if url_string value is displayed.
So if user change the value of coordinate_text, the url_tring was still returned as it take precedence over
coordinate_text