[IMP] account: rework name sequences

Task 2146469

Rework the name computation:
* It doesn't use ir.sequence anymore
* It is an editable computed field
* Add a renaming tool

This allows the user to tweak the sequences more easily than having to
get through the ir.sequence settings.

The sequence depends on a parameter of the journal: continuous, montly
and yearly restart of the sequence. Everytime a new period is started,
try to make a pattern form another period.

The incrementing is done by taking the previous name, ordered
lexicographically, splitting it by taking the digits at the end, adding
1 and re contstruct with the prefix.

** This means there could be cases where the prefix has a big importance
on the next number. For instance, if you have
INVOICE/2019/0001
INVOICE/2019/0002
and then rename the last one to INV/2019/0002, don't expect the next
number to be INV/2019/0003. It will be INVOICE/2019/0002 (again) because
the highest number was INVOICE/2019/0001.
You will then end up with
INVOICE/2019/0001
INV/2019/0002
INVOICE/2019/0002

closes odoo/odoo#41485

Related: odoo/enterprise#7189
Signed-off-by: Quentin De Paoli (qdp) <qdp@openerp.com>