[FIX] im_chat : enable chat widget only for base.group_user
[ADD] doc's readme

* also only enable linkcode if Sphinx >= 1.2
* fix html inline roles?
[ADD] support for a version switcher in odoo theme thing

needs beauty input
[FIX] base: remove test_ir_model, which causes bugs

The test in test_ir_model creates a custom model.  This causes a full reload of
the registry, which recursively installs the required modules while 'base' is
being tested.  As a side effect, it commits stuff from the database, so that
the effects of test_ir_model are actually not rolled back.
[IMP] models: "X in self" is now equivalent to any(X == rec for rec in self)

Fix modules with code like "record.id in other.stuff_ids".
[IMP] models: inherited fields are related fields read as the current user

Add an attribute 'related_sudo' (True by default) for related fields.
A related field is computed as superuser if related_sudo is True.

Add explicit related fields 'name' and 'email' on 'res.users', as these should
be readable by the public user with module website_forum.
[IMP] doc: move version switcher to header

as recommended by nwi

use same style as logo but very slightly smaller font, otherwise the
difference is a bit jarring as numbers are much bigger than the app logo's
text