[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]model: Improved read_group method to display empty column result and folded columns from related model and default_group_by field will be automatically added to the kanban no need to declare in kanban to enable the button 'Add a new column'. pass options in the read_group, In options pass 'fold_field' and 'display_empty_column' fields and remove _group_by_full methods from crm, hr_recruitment, project, project_issue, survey, website_event_track, website_forum_doc modules.
[IMP]create Read_group method for many2one but issue with maintain domain

[IMP]pass option in read_group

[IMP]fix the Domain Issue

[IMP]condition for fold field as default group_by

[IMP]improved condition for fold field

[IMP]remove unused diff

[IMP]fix typo