In odoo/documentation-user#945, the developer documentation is merged
with the user documentation in a single repository and build config.

This commit then removes source files for the developer documentation
from the odoo/odoo repository.

DOC PR: https://github.com/odoo/documentation-user/pull/945

task-2351938
task-2352371
task-2205684
task-2352544

Co-authored-by: Victor Feyens <vfe@odoo.com>
Co-authored-by: Antoine Vandevenne <anv@odoo.com>

The old tree views don't really exist anymore, this odd pseudo-flag to
dispatch between "list" and "tree" tree views has no reason to remain.

Task 1937686

closes odoo/odoo#31243

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

closes odoo/odoo#33518

Signed-off-by: Richard Mathot (rim) <rim@openerp.com>

We would like to make the "no item found" screens more appealing.

Before this commit, it shows a small help tip in the top-left
corner of the screen, just below the "Create" button.

With this commit, these help tips have been replaced by onboarding
screens, which consist of a picture and some text below, both of which
are horizontally centered.

The texts have been slightly changed, so that they are shorter and clearer.

Considered modules:

(A)
    account,
    account_asset,
    account_budget,
    account_test,
    account_voucher,
    analytic
(B)
    barcodes,
    base,
    base_automation,
    board
(C)
    calendar,
    contacts,
    crm
(D)
    delivery
(E)
    event
(F)
    fleet
(G)
    gamification,
    google_drive
(H)
    hr,
    hr_attendance,
    hr_contract,
    hr_expense,
    hr_gamification,
    hr_holidays,
    hr_payroll,
    hr_recruitment,
    hr_timesheet
(I)
    im_livechat
(L)
    l10n_fr_sale_closing,
    link_tracker,
    lunch
(M)
    mail,
    maintenance,
    mass_mailing,
    membership,
    mrp
(N)
    note
(P)
    payment,
    point_of_sale,
    post_mercury,
    pos_restaurant,
    product,
    project,
    purchase,
    purchase_requisition
(R)
    rating,
    repair,
    resource
(S)
    sale,
    sale_timesheet,
    sales_team,
    stock,
    stock_account,
    stock_landed_costs,
    stock_picking_batch,
    survey
(U)
    utm
(W)
    web,
    website,
    website_blog,
    website_customer,
    website_event_track,
    website_forum,
    website_quote,
    website_sale,
    website_sale_digital,
    website_slides

Because now is no longer required

Closes #18144

- As of v10, manifest files should be named `__manifest__.py`
- For backwards-compatibility, __openerp__.py manifest files
  will still be supported for the time being
- Limited refactoring, to add support for the 2 different
  naming conventions
- All textual references to __openerp_.py updated in
  documentation and examples

* The dashboard from the backend howto doesn't specify "name" field
  which causes non-null constraint violation.
* Some useful examples uses idea.idea" model which isn't available in
  8.0 so I replaced them with "note.note".

closes #3993