This split responsiblilies :
- portal provides basic chatter for portal document, and
website documents (slides, blog, ...).
- website_mail provides comments moderation (unpublished mail
message)
- website_rating integrate rating when posting comments

mail.thread mixin will (re)provide the field 'website_message_ids'.
Models can redifined its domain, since it can differ a bit (blog, forum,
... are not the same).
Even if the domain can differ, we still keep it on the mixin since
it will be required for the new chatter frontend (see following
commits).

This inheritance wasn't working till the commit of rco, modifying
models inheritance.
Anyway, `website_message_ids` field is already defined on several
models (product, slide, forum questions, blog post, ...), and each
of them have a different domain attribute.
So making the mail.thread mixin providing this field is not so
interessting since it will be overrided for specific behavior.
We remove this field as it can't be usefull and generic.

No functional changes, only rewrite the code with
the api.v8 which more pythonic and smooth.

- Preserved explicit 3rd-party copyright notices
- Explicit boilerplate should not be necessary - copyright law applies
  automatically in all countries thanks to Berne Convention + WTO rules,
  and a reference to the applicable license is clear enough.

Let 2015 be a year without modelines!
cf #4174

A squashed merge is required as the conversion of the apiculture branch from
bzr to git was not correctly done. The git history contains irrelevant blobs
and commits. This branch brings a lot of changes and fixes, too many to list
exhaustively.

- New orm api, objects are now used instead of ids
- Environements to encapsulates cr uid context while maintaining backward compatibility
- Field compute attribute is a new object oriented way to define function fields
- Shared browse record cache
- New onchange protocol
- Optional copy flag on fields
- Documentation update
- Dead code cleanup
- Lots of fixes