l10n_ch for v7 : Get rid of the voucher dependancy

At Camptocamp, we think that the usage of account_voucher as reconciling tool within the bank statement is not a good solution. So, we would like to separate the reconciliation process from the payment journal entry posting process.

After 1 year experience in production environnement, it appears that this module (account_voucher):
* in multicurrency environnement, can only work properly only with camptocamp patches
* the performance is poor (ex : takes a long time (up to 2 mins) to validate a 70 lines long bank statement)
* the voucher view can do many things but it is too complex for end-users (mistakes are common)
* End users do not get why we see vouchers in one menu and the same payment in the bank statements
* Too complicate to cancel a bank statement

Our vision of the process would be then :
- First step, you would import or manually post your bank transaction (and nothing more).
- Second step, manual reconciliation OR you would use a new menu to automatically reconcile invoices with payments. (this functionality already exists with the module : account_advanced_reconcile).

Consequences on l10n_ch:

Today we expect from l10n_ch the following functionalities :

* Set-up of the Sterchi chat of account + journals + default properties
* BVR customer paymenet handling : BVR invoice (webkit) + new bank type (BV & BVR / Post & Bank) + Import BVR button on bank statement
* DTA supplier payment handling : install payment order module + new bank type 'DTA' created + Import DTA button on bank statement (but reconcilaition will be done)

We want that the usage of voucher by default remains but we need to add an options in order to :
* hide in the bank statement view the last column (called payment or allocation)
* remove the usage of the voucher reconciliation using bank statement buttons 'Import invoices', 'Import BVR', 'Import payment lines (DTA)'
* Maybe (to be discussed) hide the menu created by account_voucher (payment customer / payment supplier)

inputs are welcome

Frederic Clementi
Camptocamp