Swiss electronic VAT submission (EDI, eCH-0217)

I updated the account_ch repository with a snapshot of the specification and samples for eCH-0217 online VAT submission XML.

Is there a general framework for this type of thing in Tryton already, or is it implemented entirely on a per-country / per-module basis?

We implement one electronic format per module like the edocument_uncefact or account_payment_sepa.