Index ID part of Reference field

From https://discuss.tryton.org/t/better-references-fields/177 and since #5757 (closed) we can make such index easier to declare.

assigned to @ced

added trytond type::performance + 1 deleted label

added 1 deleted label and removed 1 deleted label

New review447351003 at https://codereview.tryton.org/447351003/#ps411961003

New changeset ec58b4e2dceb by Cédric Krier in branch 'default':
Add sql_id method to Reference field and use it for index
https://hg.tryton.org/modules/account_es/rev/ec58b4e2dceb

added 1 deleted label and removed 1 deleted label

closed

New changeset fd38d58b5222 by Cédric Krier in branch 'default':
Add sql_id method to Reference field and use it for index
https://hg.tryton.org/modules/marketing_automation/rev/fd38d58b5222

New changeset 9416a55a9527 by Cédric Krier in branch 'default':
Add sql_id method to Reference field and use it for index
https://hg.tryton.org/modules/party/rev/9416a55a9527

New changeset 2f1954fe99e9 by Cédric Krier in branch 'default':
Add sql_id method to Reference field and use it for index
https://hg.tryton.org/trytond/rev/2f1954fe99e9

New changeset ad0e510a4a50 by Cédric Krier in branch 'default':
Add sql_id method to Reference field and use it for index
https://hg.tryton.org/tryton-env/rev/ad0e510a4a50

marked #7353 (closed) as a duplicate of this issue

marked this issue as related to #7353 (closed)