[FIX] purchase: keep PO currency on picking

The delivery of a purchase order was not keeping the currency and cost price
from the purchase order for the reception. This was problematic for orders where
the invoice was generated from the picking (Invoicing Control: Based on incoming
shipments). The currency of the purchase order was kept while the cost was the
one in the company's currency.
It's better to keep the currency of the purchase order to make the invoice as
it's usually the one expected (and not convert everything to the currency of the
company). opw 615555
[FIX] web: date autocompletion should not harcode 'date'

But should use date or datetime according to the widget type

This fix is related to 69d60465ee67969d72210a61a9e23204d037378a
[MERGE] forward port of branch 7.0 up to 922a52d
[MERGE] forward port of branch saas-3 up to c571413
[IMP] Remove unnecessary refresh statements because of new api
Revert "[IMP] Remove unnecessary refresh statements because of new api"

This reverts commit b213438176b16e96686d94063a3cdf6dc5c49618.
[fix] portal: typo in description

closes #3685
[FIX] ir_model: on a custom model, _rec_name should be 'x_name' if it exists
[IMP] doc: indexify index

* opt-in toc navification
* unhide index toctree, it's now back to a list of documents
* remove text thing
[FIX] tests: make sure that a failed tests does not leave the environment dirty

When a failure occurs, or when exiting an assertRaises(), the environment
should not contain fields to recompute.
[IMP] doc: more indexy index
[IMP] doc: move old API sections to orm toplevel

also move porting checklist/doc/thing to bottom of document, it's mostly
for seasoned or internal developers
[IMP] doc: try to make some bits of the porting guide less confusing
[FIX] tests: make self.assertRaises() return the expected object
[IMP] doc: rename WS page, lift to top-level
[IMP] doc: wording of method-calling introduction
[IMP] doc: have ws page take whole page width

Doc pages used container() which is width-limited, works acceptably for
single-column content but WS page takes 2 columns with code, having as
much space as possible is a much better idea.

Mayhaps it should even use lg-column(2) instead of md-column(3)?
[IMP] doc: improve index, WS page
[FIX] website_forum - replace texttext by select2 for the tags fields
[FIX] website_forum: add fake tour for people waiting the tour. To remove in master. Without it, localstorage loop to search this unexisting tour after the install...