[FIX] purchase_requisition: field date_start does not exist on purchase_requisition model so we should not use it in filters

fixes #2838
[IMP] fields: improve _determine_default() and add test for inherited fields
[FIX] account_asset: moves should use the depreciation line date
[FIX] fix wrong filter in search view (account/sale)

the field section_id is created in addon sale, but used in the account
reporting views.  This commit moves the search view definition
in the correct file.
[FIX] web: FieldMany2ManyBinaryMultiFiles must extend ReinitializeFieldMixin

The add attachment button should be displayed while being in edit mode, but not in view mode
As the widget depends on the form actual mode, the widget should be re-rendered each time the actual mode changes

This is the point of the ReinitializeFieldMixin class
[MERGE] forward port of branch 7.0 up to d36c8b5
[MERGE] forward port of branch saas-3 up to 22f2728
[FIX] account_voucher: multicompany compatibility

When the company or the journal is changed, change the period accordingly to make sure to always keep coherant values.
[FIX] calendar: gantt view argument

There is no 'date' field.
Fixes #3496
[IMP] point_of_sale: add a zero default margin when printing a receipt from the browser.
[FIX] web: many2many_binary widget upload

once widget extended with ReinitializeFieldMixin, the event binding with the binary file input and the on_file_change method can be done in initialize_content instead of start

This fix is related to d36c8b5c9bf7ab9215bc63db6ee49bec5e5b225b
[MERGE] forward port of branch 7.0 up to ae99a93
[MERGE] forward port of branch saas-3 up to c8df9fc
[FIX] fields: fix the translations of the labels of inherited fields
[FIX] models: do not copy translations of fields that are not copied

Fixes #3272.
[FIX] project: access task without project

Allow access to task without a project defined if the user is follower.
Fixes #3450
[FIX] product: pricelist shouldn't convert uom when not needed or incompatible uom types

Otherwise the Search More view will crash for example for sale order line because it will fetch the price of all products and then try to convert uoms for pricelist rule application without checking uom compatibility
[IMP] doc-ws: prepend setup code when copying from a snippet
[IMP] kanban, web: kanban tooltips and kanban states tooltips improvements.

Kanban and form view kanban selection widgets can now be dependent of the
current stage of the record. The displayed legend can be taken directly
from the stage instead of the field selection values.
- added states_legend option on kanban selection widget for kanban and form
view: used to change the selection displayed value by a value coming from the
record given by group_by (kanban) / states_legend_field (form view). This allows
customizing the kanban selection widget depending on stages.

Improved the tooltip of kanban groups customization by improving the first
implementation of group_by_tooltip parameter in kanban view declaration.
This is done by adding some options and improving the first (still not
used) implementation:
- added group_by_tooltip option on field used to group on kanban view. Its
values is a collection of fields on the record used to group. The tooltip of
the group header will be the text formed from those fields values, allowing
custom tooltips for different kanban columns.
- now all data of the kanban columns are fetched in one call instead of doing
one call for each column. The various fields to read are collected by
introspecting the view definition.

Future commits will aim at using those features various addons, notably
in recruitment, project and crm.
[FIX] product: name_get of product.attribute.value

name was confusing for bom and product if the value of the attribute is display without the attribute name
added key in context to keep the previous behaviour (e.g. in product view where the attribute name is present)