[IMP] sale: remove default "My" filters
[IMP] sale: better version of fce13a5248344981f25eecbca4856586ce7e2500
to ease migration
[IMP] event: Split Ticket: registration are now for one attendee only.

Registration are now for one attendee only. When buying several seats for an event
you have now one registration for each attendee.

event: nb_register field is removed; as well as unnecessary user_id and it subscribe /
unsubscribe behavior. Also slighly cleaned some views.
event_sale: do not auto confirm registrations linked to a draft sale order. Note: strange
origin is a char field, not a sale_order_id. Added a small wizard to edit attendees
data when confirming a sale order containing event related lines.
website_event: when buying free tickets, ask for attendee details. Added template,
controllers to handle that behavior.
website_event_sale: when buying tickets, ask for attendee details. Events ecommerce
should be better integrated with online events, using inheritance to add details
instead of being very different.
[IMP]Sale:In contract add stat button for total invoiced and due invoice amount and if an invoice is due, the contract should become pending,in the task/issues, show the alert.