[IMP] website_event_sale: validation of seats availability in cart.
Attendees are created and deleted on changing the quantity from the cart.

Added sale_order_id and sale_order_line_id fields on registrations, allowing
to find the order and the order line that created the registration without
to rely on origin and ticket.

Also fixed check_auto_confirmation, now in multi mode to avoid issues due to
the specific behavior of api.one.
[FIX] mass_mailing: updated link conversion.

Previously to this fix, url matching the same base url were linked to
the same shortened url: foo.be -> /aaa, foo.be/bar -> /aaa/bar instead of
a new shortened url.
[REM] hr_holidays: dead file
[FIX] mail : fix style (css, js and xml) of topbar button of mail.compose.message
[IMP] im_chat, im_livechat : usability improvements like, adding smiley, replace uuid by session name in reporting, modify messages order for the session form view and disabled beep when you receveive your messages.
[FIX] hr: fixed issue in employee image display in the kanban view
especially when using the group-by. Added a missing 'row', used an img-responsible
class instead of a fixed width.
[IMP] stream code from stdin through Odoo's shell

Now I have a machine gun. Ho-ho-ho.
[IMP] ecommerce onboarding misc improvements: tour, qty inc/dec, add placeholder for product desc bottom of add to cart button, add print button, cart icon fix for all themes, and last delivery module menu add to sale, so now both sale or warehouse delivery menu with access right stock.group_stock_manager and base.group_sale_manager, move from demo file to data file set for default one data as a delivery courier.