[FIX] ir_actions in website: allow to compute website_path even when creating a new server action (avoid crash then)

[FIX] stock_landed_costs: fixed several issues related to the computation and the accounting entries creation. Added a yaml test to cover the different split methods

[FIX] website_quote: scroll spy is crazy if the user change quote template. Must remove id created by the javascript of scroll spy.

This can give a performance boost on large databases
and should not be a concern in terms of access control
as the inheritance already grants access to the parent
records.

Avoid reading one record at a time, leading to multiple
calls to read() which is special-cased and even slower
than a normal one.

management to access documents in notification emails, as well as for the
'view quotation' link in portal_sale module.

models: added a get_access_action method: basically, returns the action to
access a document. It uses the get_formview_action by default (form view
of the document). However for some documents we want to directly go to the
website, leading to an act_url action for some documents. This method allows
this behavior.

portal_sale: get_signup_url now uses the mail.action_mail_redirect method
instead of directly redirecting towards a portal menu. This allows to fall
back on a standard behavior.

portal_sale: get_formview_action updated, to match actions tailored for
portal users.

website_quote: get_access_action of sale order updated. If the sale order
has a template defined, the returned action is an act_url (website view
of the quotation), not the form action anymore.

mail: fixed signature + company signature in notification emails. Even without
user signature, the company signature + access link should be correct.

portal: signup url in notification emali was not using the mail redirection
as action. It is now the case.

[FIX] email_template: when generating body containing the user's signature, add it as html as it is now pure html, not plaintext anymore.

[FIX] mail: compose wizard: fixed default_get overrides not correctly managing the received field_list + improved custom call to default_get to correctly manage its in and out values.

[FIX] crm: fixed day_open and day_close computation (conditional store + be sure that date_open and date_closed fields are set)

[FIX] project_issue, resource: fixed computation of hours / days to open (assign) or close an issue. Those fields now have a conditional store, because they were not recomputed even when changing date_open and date_closed. Changing the stage now correctly changes the date_closed. Also added some fixes in resource module, the date was not correctly taken into account when computing the number of working hours between two dates.

+ correct tests

As `_inherits` fields are now handled via `related`
fields (not stored, obviously), a new descriptor
`searchable` has been added to `fields_get()` result
to indicated if the field is searchable or not.

Added a record of im_livechat.channel in website_livechat data

(partial revert of 44a5268c)

[FIX] hr_contract: count the number of contracts of an employee as superuser_id as this field is required in the form view. However no data is displayed, and no data about the contracts are leaked, so no security holes.

Before, the field purchase_ok was set as readonly on the product form if the product wasn't a variant, to avoid users to set all the products variants associated to the product template to be set as purchase able in one action.

We now consider that this can be done by the end user

opw-611106, when clicking quickly Sales > Opportunities than Sales > Leads.

(rebase of #1534)

[FIX] point_of_sale: partner list rendering was not refreshing correctly. + limited display to 1000 partners for performance reasons

of switching back to default screen.

This is used by the soon to be merged restaurant addon to create new orders
and display them at a particular screen.  However, this behaviour is more
confusing in the other cases, so I'll think of a better way to solve this.

[IMP] pos_discount: a new pos extension that allows you to quickly give a global discount on the current order

[IMP] point_of_sale: made the server data loading more modular for easier development of point_of_sale extensions

[IMP] point_of_sale: add debug popup that displays unsent order data, for when localStorage is hard to inspect

Conflicts:
	addons/point_of_sale/static/src/js/widgets.js