* Convert some CSS to LESS
* Split/Join LESS files
* Remove duplicates between website and web_editor
* UI improvements
* Allow simple customizations thanks to LESS var&mixins for website

Before, the whole editor UI was redefined for web_editor, each
mass_mailing template, website builder, ... Now they all inherit
from the web_editor one.

* Delete useless snippets
* Delete default mb,mt on snippets
* Delete useless options
* Reorganize snippets order
* Style improvements

This key in context is useless since v7.0

Update Dialog class with enterprise version.

- `ir.property`, improve API of method `get_by_record`
- `res.bank`, `res.partner.bank`
- `res.company`
- `res.config`, `res.config.installer`, `res.config.settings`, fix usage of methods `get_default_`
- `res.country`, `res.country.group`, `res.country.state`
- `res.currency`, `res.currency.rate`
- `res.font`
- `res.lang`
- `res.partner`, `res.partner.category`, `res.partner.title`
- `res.request.link`
- `res.groups`, `res.users`, `res.users.log`, change password wizard

Rename the menu 'Apps' by 'Local Modules'

Fixes #9009
Closes #11017

pos_order.onchange_qty was renamed to pos_order._onchange_qty during the
migration to the new API.

This makes it so that when you set a customer in the POS frontend it
will automatically apply the fiscal position associated to the customer
on the order.

If the customer has no set fiscal position or if the fiscal position is
not available in the POS nothing will happen.

opw-668155

This was not really possible before. This prepends a dummy undefined
fiscal position to the selection list that'll clear the current fiscal
position when selected.

Also considered was using the "Cancel" button of the selection widget to
clear the fiscal position, but that doesn't make a lot of sense from a
UI point of view. Pressing a "Cancel" button shouldn't change anything
in the underlying model, it should just get rid of the dialog window.

opw-668155

Before this, seeing the current set fiscal position on an order was not
really possible.

opw-668155

- Hide account_id field and add a required project_id field on timesheet entries
- Remove is_timesheet field: as project_id is only required for timesheet entries and not for other analytic lines, it can be used to determine wether a line is a timeheet entry or not.
- Remove project_timesheet module as all its functionalities are moved to hr_timesheet
- Replace timesheets on contract option on products by timesheets on project
- Small fixes and improvements in timesheets and projects views and groups

Let the default values choose the correct image by setting correct
value in context

Also allow to search on archived carriers easily.

add_payment is no longer an api.model so self represent the current order

- report.transaction.pos
- report.sales.by.user.pos
- report.sales.by.user.pos.month
These reports where not called anywhere and have been replaced by pivot views

Remove order reports that can be easily replaced by use of the pivot view of
report.pos.order
Add a session_id field and a filter on report.pos.order to make it equivalent.
The invoice report is only useful when called from the pos UI so keeping the
report but not added in the print menu

Never called or not used

complete_name is actually the existing orm field display_name
field iface_fullscreen is never used, cf TODO

Never called

For textual attachments (like assets), the indexed content is the
content itself. Avoid prefetching this potential huge field.

When deleting attachments, only delete files once.

Previous implementation was expecting exactly the same number of
attachments than the number of assets in a bundle. However it's
possible that duplicated assets are created due to concurrent first
generation.

This duplication cannot be avoid, but is cleaned upon next bundle
regeneration.

Joint work with @sle-odoo and @odony