[IMP] gamification: avoid sending twice emails in cron

When the cron is running on a database with a large number of goals (e.g. website_forum with thousands of users), it's possible the CPU time is exceeded and we may have a rollback after sending some emails (for granted badges).
To avoid sending twice emails, commit in cron mode after each reward.
[FIX] point_of_sale: prevent empty order creation as they are not accepted by the backend
[FIX] website_sale: save the company in street and the street in street2.

The old behaviour was not better, because when we print the invoice, the order was ugly:
    Name
    Street
    Company name
    Country

Now we will have:
    Name
    Company name
    Street
    Country

This patch is not retro-compatible:
   Old partners will see the address in company name and vice-versa.
   Need to update view and switch street field and street2 field
[IMP] website_event: add mail subtypes

Add published and unpublised mail subtypes, to track events publication, and to be able to follow these subtypes
[FIX] kanban: remove container=element for tooltips on kanban
[FIX] dict notation for js reserved words in options (Fixes #2957)
[FIX] pos_restaurant: Issue 614981: product renaming from name to display_name was not done in the pos_restaurant module, resulting in empty product names in various places
Revert "[FIX] Error when installing module document"

This reverts commit 8dd4c83d9cf6f45ca39f120b296c1c69079154a4.
It does not fix the issue, but hides it instead.
An actual fix has been made since.
[IMP] mail: parsing emails with several html parts

If an email contains several text/html parts inside a multipart email, the previous code was only keeping the last content part.
The Content-Type: multipart/mixed allows several independent part (RFC1341 7.2.2), so two html is technically valid.
With this patch, the two parts are concatenated. (opw 614755)