[m2m] in tree view has hardcoded seperator

[Sandy Carter (http://www.savoirfairelinux.com)]

Problem:
There is no option to change the separator in a m2m representation in the list view.
This is a problem with name_gets which contain commas, such as the base_location module in lp:partner-contact-management. A semi-colon(;) or pipe(|) separator is preferable in that instance.

How to reproduce:
Have a tree view which displays a many2many field.
Add a couple of entries for which the name contains a comma.

Actual output:
No way to tell the difference between different elements

Expected output:
An option to the field for which you can change the comma for another character.

[Sandy Carter (http://www.savoirfairelinux.com) (sandy-carter)]

Forgot to mention, the line which hardcodes the comma is here in the render cell function of instance.web.ListView.List in addons/web/static/src/js/view_list.js around line 1066 as of revision 4137:

                        record.set(column.id + '__display',
                                   _(names).pluck(1).join(', '));