[FIX] project, project_issue: when no project in context, display default
columns in kanban view. Also fixed some issues in the issue kanban view.
[IMP] crm: opportunity kanban view: display tags.

[FIX] crm: opportunity kanban view: description of a crm stage is requirements
not description.
[IMP] im_livechat : add nbr_sessions field on channel and modifications of various views
[IMP] im_livechat : add rule to display (or not) the support button.
[FIX] fix debug mode: correct id and xml_id (web client)

This commit fixes two issues with debug mode:
* when a default searchview is requested, it is
initialized without its view_id. Problem is that it prevents debug mode from editing the view.
*  add xml_id in Edit action form view(debug mode) : this makes the xml id visible in form view
[FIX] web: radio buttons

removed js that let user to uncheck radiobutton and from addons removed radiobuttons used for not required field except sync_typ.
changed this field as required because of functional requirement
[IMP] mrp: BoM name is now accessible to the 'manage multiple level
of bom' group, not the properties group. Indeed this will allow more users
to see and search the name.
website_event_sale: validation of seats availability in cart.
Attendees are created and deleted on changing the quantity from the cart.

Also fixed check_auto_confirmation, now in multi mode to avoid issues
due to the specific behavior of api.one.
[FIX] Fixed the traceback occured while clicking on the CONFIRM SALE from quotations where self is used instead of sale_order and fixed the issue of warning which is not shown when no seats available in the cart.