[IMP] mass_mailing: campaign form view: add a stat
button to go to the campaign mailings + its function field to have the
counter.
[IMP] hr_holidays: when searching on holidays.status with an employee_id in
context and no specific order, order on limited leaves then on remaining leaves.
This is usefull for users having their normal leaves being displayed in top of
the list (legal leaves, compensatory leaves, then sick and unpaid for example).

Also updated the name_get of holidays status, displaying (remaining leaves /
max leaves) instead of (taken leaves / max leaves). What is important for
users is the number of remaining leaves, not the number of leaves already
taken in that type.

Also updated and reindented demo data (compensatory is now limited + order
of declaration due to this change).
[FIX] website_forum: post: if no create_date, relevancy is 0.
Fix a crash when creating a post in backend without create_date being set.
[FIX] web_tip: avoid tip on invsible element, causing some
display issues.
[IMP] website_blog : allow multi tags and date filter, clean all the routes, remove group_comment from website_mail (only user and portal can post comment on blog.post, but the form is visible for all), modify the redirect controller to the login form when posting comment, and remove the description field of blog.blog
[FIX] web: fixed display of datepicker in editable list view.
The icon was quite board, leading to ugly and sometimes too short display
of the date itself.
[IMP] fleet: usability improvements :
- simplifed name of vehicle model; the name is now the model name; the old function
is used to compute the name_get.
- added Suzuki data
- parent of a cost is now hidden except for technical group, because it is the
same as the vehicle
- fixed some vehicule -> vehicle typos