[MERGE] [IMP] Mailing lists usability improvements: headers related to mailing lists, use of email queue for notification emails (> 50 followers), archive website template imp and fix.

Happens when trying to change an image in a a banner block

This is a temporary workaround until these fields are removed from the template or the view is more explicit about the meaning of this field (the one on the first variant)
Fix #542

[FIX] STOCK: Fixed the warning tree_view_ref fully-qualified name.

[FIX] STOCK: Fixed the warning '' 'tree_view_ref' requires a fully-qualified external id (got: 'view_move_picking_tree' for model stock.move). Please use the complete 'module.view_id' form instead. ''

[FIX] website_sale: retur the browse record of category insead of int

[FIX] product_email_template: fixed a bug preventing from sending emails and therefore from validating invoices when having templates without attachments linnked to a product.

[FIX] event_sale: avoid traceback when remove product in onchange view

[FIX] [IMP] website_forum: usability fix: moved answers / votes column below the text on mobile displays, because it takes too much place and restrict the place left for the text. By the way some custom css has been removed, replaced by bootstrap css.

- added possibility in mail to have a model adding custom headers in emails sent for notifications for new messages
- mail.group now add list-id and precedence: list in the headers to inform mailing systems that those mails are to be considered as mailing lists
- website_mail_group adds some further data in the headers (subscribe, unsubscribe, archives)
- groups page now display the number of message in the last month
- notification emails are now queued after 50 recipients

[FIX] Account, l10nbe - Respect name_search operator for account.account, so = really work as expected.

Also fix data file in l10nbe which was relying on the old implementation.

[FIX] l10n-be data - Be more accurate in the belgium data. All accounts have by default a right padding of 0 to be on 6 char, so the csv need to have the accounts on 6 char since with have removed the default replacement of "=" by "=like" to allow the manual import

sale_order module override state field of sale.oder (sale.sale.py) and forgot to reset the track_visibility, therefore sale orders state changes are no longer tracked once this module installed.

This will make sure already processed rules are persisted
in case a timeout occurs while processing the next ones,
ensuring that *some* progress can be made in most cases.

A safety guard already in place prevents the recursive
trigger of rules while another rule is being executed,
as a simple measure to prevent endless loops.
This guard was missing when processing time-based rules.

A programming error introduced at rco@openerp.com-20121220142445-emzzvhlw400q37c9
fails to properly check when a rule has already been executed in the past.
Time-based rules should only be executed if the trigger date is in the past and:
 - either they never executed before
 - or the last execution date is older than the trigger date

Executing a rule always updates the `last_run` value, which would
always force a useless registry reload to occur. Only signal the
change if the rule applies to a model that was not previoulsy
monitored for base action rules.

[IMP] account.move.line: extra index on (date, id) corresponding to the default _order, courtesy of @gurneyalex.

 Fixes https://bugs.launchpad.net/openobject-addons/+bug/1311004

[FIX] delivery: add missing information in chained pickings

[FIX] hr_timesheet_sheet: correctly set the employee on the attendance

The field note on account.fiscal.position and account.fiscal.position.template should not be translatable in classic modules.
The l10n_multilang module is intendend to make chart of accounts multilang and is the place to set translate=True

[FIX] website_forum: people having enough karma can accepts answers on every question, not just their own. Fixed the condition computation.

We always want to escape quotes (") as part of the process of
generating HTML output. This option (quote=True) turned into
an implicit flag with a DeprecationWarning in werkzeug 0.9.0
It is likely to disappear in a future release of werkzeug too.
A wrapper avoids this warning without loss of compatibility

[FIX] logging PostgreSQLHandler: mute sql_db logger to avoid logging loop if db connection or query failed

[FIX] delivery: do not remove the delivery method on the sale.order when adding it as an order line (useful information)

If the writeoff_amount is above 0, the fields writeoff_acc_id can be displayed and is required depending of the payment option. If the writeoff_amount is reset to 0, this field should no longer be required.