`action_post` does not always get used by odoo methods; need to plug into `_post`.

In the process, fix README & add SQL index.

There is no more need to set an accounting date as the usual date is now used.

add new files
fix pipeline requirements

 : Reviewed migration, play_onchanges usage, and unit tests

in case other modules also install companies.

This would happen when running tests on a DB where ``account_period`` is
already installed.

Follow-up on rev 7bde6eae1dcf.

Also update tests in this module to use them instead of creating them anew.

To be reworked.

or an accounting document.
Updated the translations.

Specifics to play better with accounting changes:

* No longer change the base ``date`` field; add ``accounting_date`` instead.
* Build periods when loading accounting data for a new company.

The copy of a transaction_date should be disabled by default.

Updated the translations.
Updated the unit tests.

Note that when the account move date is empty an exception:
constraint null value is raised during execution of action_move_create() method.

Add force_period_on_date context to always make the period be around the current date.

Note that we send a accounting date in reverse_moves func and
the fill_acocunting_date should use it instead of today date.

Remove a "special" field & rename an action.

Updated the translations.
Executed "black" and "isort".

it existed in previous versions