[FIX] load view from file shall not raise an exception

In --dev mode, when a view can't be loaded from the file in spite of
being referenced in field `arch_fs`, the current behavior is to raise
an exception. In most cases, developpers don't want the view to fail
so the behavior has been changed in favor of a logger warning and
a fallback to `arch_db`.
[FIX] website_mail: "save and continue" button
[TYPO] project_issue: efficiantly --> efficiently
[CLEAN] website_event_track: cleanind / migration to new api of the module
- removed event.tag and event.track.stage models
- cleaning / linting
- fixed kanban view of tracks
[FIX] web_tip: better event handling

* Override message_fetch from mail.Thread in a dedicated limk module (mail_tip)
and fire an event when the messages are loaded. This is necessary for tips on
the chatter.
* Override render_value form web.form.FieldStatus: Call reposition() when a
FieldStatus object is done rendering.
* Tip.reposition() method
* Handle web bus resize event
[REM] association: empty file
[REM] association: removing a file is good, but it removing from the manifest is better
[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] payment, website_sale: better control of sale order confirmation in ecommerce.

Auto confirmation is now controlled by a field on the acquirer
that proposes to confirm
- at payment (Pay Now button on ecommerce)
- at payment confirmation (transaction feedback)
- never

Also fixed the state of tx for transfer transactions that was modified
for debugging in a previous task but not reverted.
[IMP] hr_recruitment: switched job state selection order
[FIX] hr: fix traceback when updating manager of department (ids is already a list, not necessary to list it)
[IMP] website_quote: onboarding

Views and labels improvements
[IMP] mrp, stock: default uom missing value when importing from csv
[REM] website: my_account link under user menu

This link is not useful anymore as we do have frontend/backend menu
integration since Odoo v8.0.
[IMP] website_hr_recruitment: resume in chatter
[ADD] website slides module
[FIX] broken view xml
[REF]: refactor clides to adapt channel concept

[IMP]: implement like button

[IMP]: add like button on slide detail view

[IMP]: different aspect ratio for slide and video

[IMP]: improve channel landine page