[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.
[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] 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)
Forward port of 7.0 up to rev 9b87d6f
[FIX] correctly forward context in graph view

the new graph view silently ignored the context when doing its rpc
read_group.  Usually, it's not really a problem, which is why it is only
now being fixed, but some models actually use the context in read_group.
(for ex, account_entries_report)
[FIX] account_voucher: convertion rate of purchase receipt

The conversion of currencies in vouchers are made based on payment_rate_currency_id field (instead of usual currency_id).
This field was not present in the purchase view and not correctly set when we change the journal (and thus the currency) which was leading to rates of 1. With a rate of 1, the amount is equal to the currency amount (which is rarely correct). opw 611254
[FIX] auth_ldap: remove unused sql column
[FIX] account_voucher: import invoices, sign according to transaction type
[FIX] website_blog: portal users should not be able to read unpublished blog posts
[FIX] widget html: rendering issue in mail composer on Firefox
The cleditor width does not include the margins. Setting 100% will make the editable area too large (104%) on Firefox (opw 611700).
This issue was already fixed in newer releases, from commit 9247c37de7d67beb479905e218656665dc12391f
Nevertheless, it introduced a new issue: while editing the form, the content of widgets html which were located in hidden notebook pages weren't displayed when displaying the page content.
opw-614448
[MERGE] forward port of branch 7.0 up to 9c77f79
[FIX] stock: error on stock.partial.move creation

The stock_partial_move wizard removes the required attribute for the field picking_id on a stock.partial.move. This means that we could get moves without picking_id and the previous line was failing ('NoneType' object has no attribute 'currency_id'). opw 614531
Forward port of 7.0 up to rev 4a064b9
[FIX] web_calendar: reset dataset index if search result empty
[MERGE] forward port of branch 7.0 up to 5c2fb12
[FIX] point_of_sale: invoice not created in backend

Missing arguments that lead to the invoice not created in the backend (opw 609470).
[IMP] stock: do not generate empty backorders

If every line of a partial delivery is at zero, do not generate empty backorders (opw 608680)
[FIX] crm: correct open lead or opportunity view from calls

When opening a lead/opportunity from the phonecalls view, we did not open the correct view (always the lead).
This will use the type of the crm.lead to determine which view should be used, opw 608493.
[IMP] stock: Optimize stock_move.setlast_tracking()

When setlast_tracking is called on a large number of moves in a picking
(e.g.  when splitting moves in a picking), the time to complete grows
exponentially.  The reason is that it loops over all the moves of
a picking, even if it keeps only the last tracking.

The method now uses a search() with a limit so it doesn't need to browse
all the moves.

Added test to check the behaviour of setlast_tracking
Fixes #2448
[INP] portal_sale: remove buggy context

Even if this should never be used in normal portal environment, if a user with enough access rights tries to create an invoice, this would crash. We don't need context here (opw 612591).