Clickable many2one fields for tree views

This module changes how list views behave when they show a link to another record (a many2one field, such as the customer on a sales order or the product on an invoice line).

• In any list view, an extra small arrow button appears next to each many2one value that has a record set.
• Clicking that button opens the linked record in a form view, in the current window, instead of opening the row itself.
• The button only appears when the field really is a many2one, has a value, and the column is not marked to hide it (a column option called no_open).
• Any context defined on the column is passed along when opening the linked record.

It works everywhere list views are used, including the lines of sales orders, purchase orders and invoices, because it patches the standard list renderer (ListRenderer) of the web client. No new menus, models, reports or scheduled actions are added; the change is purely a user-interface convenience. The module is in the Hidden category and depends only on web.