[16.0][ADD] account_analytic_category (replace account.analytic.group)

[norlinhenrik]

2 new modules with 2 new fields on account.move.line to use in pivot:

• account_move_line_analytic_account_ids: new field analytic_account_ids.
• account_analytic_category: new field analytic_category_ids.

[norlinhenrik]

Waiting to merge analytic_mixin_analytic_account, see #565.

[norlinhenrik]

Maybe a better implementation would be to create an analytic_category_distribution JSON field on the account.move.line?

EDIT Two observations in 16.0:

• account.analytic.plan has parent_id. Having one parent for all plans improves the UI.
• account.move.line has analytic_account_id. In pivot view, I can group by Analytic Account.

account.move.line with analytic_plan_id is really what I am missing. I would like to group by Analytic Plan.