[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.
[IMP] website_sale: Show error message if VAT number, Email is invalid.