[FIX] account_anglo_saxon: correctly set the accounts for returns

The generated moves on a return should be the reverse of the outgoing move.
Fixes #1817, opw 604417
[FIX] mail: chatter read more/less expand first oe_msg_body_long/short in the first oe_msg_body

Otherwise, if the mail itself contains a oe_msg_body_long (because sent in the mail history), it will open that one
[FIX] stock/purchase: dates and currency rates

Use the currency rate of the purchase date instead of the one of at the reception time (opw 610430)
[FIX] hr_timesheet_sheet: avoid error when sort attendances

When an attendance line is edited, the tuple has no key 'name' which lead to a traceback.
Fixes #546
[FIX]stock_landed_costs: Fixed wrong costs on landed costs with many products
[FIX] mrp_repair: pass context in product_id_change calls
[FIX] kanban: wrong condition to reset the dataset index

The dataset index should be reset either if the dataset is empty or the index is greater than the records size
[MERGE] forward port of branch 7.0 up to a218a9e
[MERGE] forward port of branch saas-3 up to 5bd0249
[FIX] event: translate templates into user language

When sending an email of the registration/confirmation, the context was lost and the tempate sticked in en_US.
With the patch, the template will use the current user's language.
[FIX] website_sale: displayed price doesn't change for 'List View of Variants' customize template
[FIX] Packaging: Wndows: wrong handler used when logging to file
[IMP] stock: display translated selection value in message

When a user tried to delete a done or canceled picking, the error messages used to display the key of the selection field ('done' or 'cancel') which was surprising in other languages than English. This patch takes the string value of the selection field, keeping the context to get the translated value (opw 613068)
[FIX] web: form: quick create: name is now required to avoid creating records with a void name
[FIX] product: Even when the product template has more than 1 variant, the default_code is displayed.
[FIX] bus, im_chat, im_livechat : use correct session to rpc call, little refactoring of im_livechat js, and prepare js code for Odoo Support.
[FIX] base_gengo, website_gengo: groups on the gengo key.

Basically the admin group can read the gengo key. When adding website_gengo that adds the
website groups, the groups allowed to access the key are updated.

This is done because in base_gengo the website groups are not necesssarily defined. Website
is not a dependency of base_gengo.
Merge pull request #2550 from odoo-dev/8.0-fix-default_code-chm

[FIX] product: Even when the product template has more than 1 variant, the default_code is displayed.
Merge pull request #2543 from odoo-dev/8.0-fix-website_sale-list-variants-chm

[FIX] website_sale: displayed price doesn't change for 'List View of Variants' customize template
[FIX] purchase: keep fallback behaviour that was removed at rev 8973217

If no valid invocie is found on the purchase order line, use the price and currency of the line (coherent with help message)