[FIX] models: stored func fields computation on one2many write

On one2many fields writing in an existing record (not when creating new record), the computed stored fields of the one2many were not re-computed correctly
Computed stored fields were marked as modified only if no_store_function was not set to True in the context. no_store_function is set when writing one2many records on an existing record.
Now, these computed stored fields are marked as to be recomputed, but are recomputed later, at the end of the existing record write
[FIX] models: `_convert_to_write()` shall not return `NewId`

The result of _convert_to_write() is intended to be pass directly to
`write()` or returned to the client (`onchange()` and `default_get()`.
`NewId` is as special value that must not be stored into the database
or exposed to the client.
[FIX] point_of_sale: the product name field changed to display_name to include variants information, this should be reflected in searches as well.
[FIX] point_of_sale: the order uid were generated via timestamp, which were not sequencial or easy to understand, they are now generated with the order id and order sequence number which are sequencial
[FIX] point_of_sale: invoicing in the pos printed the wrong order due to a mismatch between order ids and invoice ids
[IMP] models: improve code of _convert_to_write(), make it easier to read
[FIX] product, point_of_sale: add a display_default_code context option that can remove the internal reference (default code) from the displayed product name. Used in the point of sale to unclutter the receipt & GUI
[FIX] mrp_operations: use list instead of record set for o2m

In v7, accessing a o2m returned a list of browse record while it returns a recordset in v8.
The method _move_pass expects a list so a manual conversion is required.
Fixes #1787
[FIX] website_forum_doc: fixed tree view impossible to use to create new chapters (missing forum_id due to wrongly copy-pasted views) + fixed max width of images displayed in the doc.
Merge branch '8.0' of github.com:odoo/odoo into 8.0
[FIX] point_of_sale: copy/paste error, super must use the apropriate class
[IMP] Cache bundles in ir.attachments instead of LRU
[IMP] website_quote: handle quote and website descriptions

Add field quote_description on product.template and turn website_description from sale.quote.line into a related.
Overwrite write and create methods to synchronise both fields when setting a product.
website_description on product.template is added by website_sale but there is no dependency relations between these modules so we need to define it in both modules.
merge from odoo/8.0